7 ms·

Show HN: Capsule – Single-file web apps that save their data into SQLite

298 points by bashtian 20d ago

Hey HN, I always had the problem that building HTML pages is really simple now, but trying to save data required hosting it somewhere, and sharing it afterwards was not easy. Over the last few months, I've been building an app called Capsule (it’s also the file extension name) written in Rust with Tauri 2.0 that allows packing an HTML app and its data into a single SQLite file. The HTML file and any related assets are directly embedded in the database. User data can either be saved as a localStorage key/value store or via a MongoDB-inspired collections API as documents, saved in a table in the file. You can also save other assets, like PDF files or images, directly in the database to keep different documents together. All data can be easily exported to CSV or JSON if needed. Privacy and security were a big priority for me, so documents cannot do anything out of the box. They don’t have direct access to the file system and they require permission to access the internet. The permission model is still something I’m working to improve. Capsule documents can also use local or remote AI models for document specific AI features. One downside with this approach is that multiple people working on it will create different copies. To make it possible to merge different copies of the same file, each data entry has a unique UUID and timestamp. I’m planning to open up the file format specification for the 1.0 version of the app so other apps can read or write Capsule files. You can try it out in the web preview at https://withcapsule.app/preview https://withcapsule.app/preview with pre-built templates or use any AI provider of your choice to create a custom, Capsule-optimized app by using the following prompt: "Please read the app wizard instructions at https://withcapsule.app/prompt.txt https://withcapsule.app/prompt.txt and help me design an app.“ I’m still working on the file format but there are migrations for each new version, so data should never be lost when using newer versions of the app in the future. Please let me know if you have any ideas or use cases where this might make sense or does not work.

p32929 18d ago
[flagged]
andai 20d ago
That's pretty cool. But who is this for? What problem does it actually solve? How would I know if I need this, vs something else?
- bashtian 20d ago
  If try to do data management in Excel or need to download an app just to save some recipes, this could be an alternative. For example you can track time and billing with a nice UI without requiring a SaaS subscription. You can try some examples in https://withcapsule.app/preview https://withcapsule.app/preview
lewisjoe 20d ago
This is great. Curious: this requires users to have a host app installed on their machine that can read .capsule file right? Won't that be a point of friction for distribution? Isn't html/css a better distribution mechanism as most computers already have the tech to run them?
- bashtian 20d ago
  The problem is that you can't save the user data in way that you can click a single file, similar to a Word or Excel file. I you think a about it, a Excel spreadsheet is also just UI + data in a single file.
  - paweladamczuk 20d ago
    This is a frustration of mine as well, but I vaguely remember someone showing something on HN where the file could essentially save itself, I think they were using some file APIs for that... sadly I can't find the details anymore. But I keep running into the "HTML file opened locally can't update itself" issue repeatedly now that I build tools for myself with LLM agents.
    - yoz 20d ago
      The File System Access API can do this, and it works in local ("file:///") HTML files, but it's only currently supported in desktop Chromium browsers: https://caniuse.com/native-filesystem-api https://caniuse.com/native-filesystem-api However, every browser will let you download a new version of the HTML file and save it over the old one - yes, even from a local HTML file: const blob = new Blob(['<!DOCTYPE html>\n' + document.documentElement.outerHTML], { type: 'text/html' }); const a = document.createElement('a'); a.href = URL.createObjectURL(blob); a.download = 'mypage.html'; a.click(); ... but you need the user to do this for every update. So we're back to manual "Save" buttons.
      - Jonovono 20d ago
        This is the approach Bento took I believe (similar idea, but just for decks): https://github.com/nyblnet/bento https://github.com/nyblnet/bento. Saw it on HN a few weeks back
pmkary 20d ago
Really really nice
bezko 20d ago
[flagged]
eleventen 20d ago
You can get a cheap approximation of this with chromium browsers + Filesystem API and a PWA manifest for that native-ish feel. AI has reignited my interest in building based 100% on browser native features. https://developer.mozilla.org/en-US/docs/Web/API/File_System_API https://developer.mozilla.org/en-US/docs/Web/API/File_System...
- bashtian 20d ago
  If you want to distribute apps to many users this would probably be a better solution. The main benefit of Capsule is the personal document like app. You create a capsule, move it to an USB stick, save it in your cloud storage and it's still the same document. Nothing has changed, not the UI, not the data. The document will stay the same.
  - ramon156 20d ago
    how is a filesystem supposed to prevent you from doing that?
  - al_borland 20d ago
    If it’s web native, anyone can just use it. If it’s a capsule, they first need to download the capsule app to associate the file extension with the OS and have it launch, right? That feels like a big barrier, almost like a Java runtime.
    - eleventen 20d ago
      In defense of capsule, the Filesystem API is janky and has kind of shit UX. Less sophisticated users would probably prefer the UX of a purpose built tool. I prefer worse UX for the sake of standards and zero install, but many people would prefer the opposite. I don't think Capsule is intended for the HN crowd.
zackify 20d ago
love this idea!
gadders 20d ago
>>Capsule packs your entire app — UI, data, and everything — into a single portable .capsule file. I'm having Lotus Notes flashbacks.
- p2detar 20d ago
  Indeed. But Lotus Notes actually had the design and data stored independent of one another and you had database templates. You could update your design without breaking the data, or even have entirely different design that works with the existing data model. This capsule thing seems to store the design itself within the database, which is odd to me. I guess I don't get it at 100%.
  - gadders 19d ago
    Yeah, it's not an exact match. But I could email you a lotus notes nsf file and you could open it in your Notes client and have the data and the application in front of you.
dgf18 20d ago
Many big companies are starting now to test agentic coding to automate business processes. This could be a nice tool to distribute apps for workflows that aren't big enough to justify the operational overhed of maintaining a traditional web app backend. Nice!
- m-p-3 20d ago
  This sounds like the modern take on MS Access.
lolakutty 20d ago
What is wrong with using IndexedDB?
- bashtian 20d ago
  For saving data in the capsule file it would create complexity regarding migration handling when updating the HTML file to add a field to a form for example. Keeping the data schemaless makes it also easier for merging data or importing data from a CSV.
  - lolakutty 20d ago
    Doesn't indexedDB have builtin migration mechanism? >Keeping the data schemaless makes it also easier for merging data or importing data from a CSV. Not sure how it makes easier. There is always an implicit or explicit schema. IMHO explicit is often better.
fdeth 20d ago
So, let’s do Visual Basic again, but this time with LLMs and web stuff.
blamestross 20d ago
Seems very "packable into a standalone binary" but doesn't seem like that is a planned use case.
- bashtian 20d ago
  The problem would be cross-platform support. In the end the capsule file is the standalone binary similar to a PDF or a Word document, you only need the viewer app to open any capsule file.
  - blamestross 20d ago
    you can trivially bake X binaries if you have the viewer app for each platform. This is the normal way to distribute software for cross-platform support. I might just be hyper-defensive to any sort of vendor lock-in like a "viewer app".
tonymet 20d ago
is the idea this would be hosted or run locally (like Electron)?
- bashtian 20d ago
  This is for local document like apps. Tauri is actually using the OS webview instead of bundling Chromium like Electron. That's why the download is only 10MB for Mac.
  - tonymet 20d ago
    i like that idea. Anything that improves native OS UI, responsiveness (120hz) and reduces resources is a good idea.
redog 20d ago
This seems ripe for an injection attack. Can it be inspected before running?
- deleted 20d ago
  [deleted]
jawns 20d ago
My take: If your app needs to update and preserve state (using SQLite or any other DB), it is probably not something you want to pass around as a bundled file. Or at least, it's extremely limiting, compared with hosting it somewhere on the web, which is not that hard to do these days. Think of the workflow: Any time the state changes, you need to email a new Capsule file to whoever else is using the app. And one would think the state would change at least occasionally, because otherwise there's little reason to use a DB. Alternatively, you can just host it on the web, the DB state dynamically updates, and it's automatically available to anyone with app access. Isn't that a lot simpler?
- Reviving1514 20d ago
  Why not on a shared drive like dropbox? Concurrent editing wouldn't work, though.
  - teraflop 20d ago
    Beyond "not working", concurrent editing is likely to silently lose data, or corrupt data, or possibly just fill up your drive with lots of "conflicted copies" that you have to manually reconcile.
    - dizzard 20d ago
      When I read about this project, it doesn’t seem like concurrency is much of a concern. I think it’s _supposed_ to be treated like sharing a document with someone else. If a capsule is a recipe, like in one of the examples, that’s pretty cool. If a capsule is a recipe _manager_, then I think it would get messy.
- latexr 20d ago
  > Isn't that a lot simpler? You’re glossing over the recurring cost and annoyance of dealing with the hosting and having to secure the data. This way you just share and it’s local. Sure, if you have to share data between people, your points are valid. But this seems like a way to build apps geared for individual users, like a notes or recipes app.
tamimio 20d ago
New way to deliver viruses just dropped! Great idea but it can be abused for sure.
- bashtian 20d ago
  The HTML files does not have any permission to access anything on the file system. Ideally the whole app will be running inside a sandbox on desktop, for mobile apps this will be the default anyway.
thederf 20d ago
I've been working on this exact idea, with sqlar as the "format specification". Works in the browser, and desktop + Android using Tauri. https://github.com/JoshTheDerf/uapp https://github.com/JoshTheDerf/uapp Demo apps and games: https://thederf.com/uapp/demo/ https://thederf.com/uapp/demo/
- windsurfer 20d ago
  FYI requests from your demo are being blocked by CORS in Firefox and it never loads.
  - thederf 20d ago
    Thanks for the heads up! Fixed now, was a bug in the service worker.
- deleted 20d ago
  [deleted]
sigmonsays 20d ago
if state is best shared, why keep it w/ the code? You're gonna end up having to build a complex state sync system to a central DB anyways...
olaulailadila 20d ago
An idea for a killer feature: Make it so that auhors can expose their capsules to the internet, and the people whoe wants to use them(lets call them users) can type the name(lets call it address) of the caplsue into the app, and your program will pull that capsule in the the users device..
- derpyzza 20d ago
  wow, that sounds revolutionary.
- ligarota 20d ago
  Hear me out. Here is the name PWA : Probably Web Again
- saejox 20d ago
  nice. we should call it web, like spiders' web all connected.
dzink 20d ago
Looks useful, but the Mac download shows "“Capsule” is damaged and can’t be opened. You should eject the disk image." and then you realize it could be ripe for malicious payloads as well.
xd1936 20d ago
"No cloud. No accounts. Just share it." close tab
- j-pb 20d ago
  yes yes we get it, you don't like AI ...
- mionhe 20d ago
  Can you elaborate a little?
  - al_borland 20d ago
    It reads like the whole thing was vibe coded and 0 work was done beyond what the AI spit out.
- derpyzza 20d ago
  well that's a first
razerbeans 20d ago
I love this idea! One of the fallouts from widespread AI adoption that I've seen: They're very good at creating visual artifacts, but if you ever have to provide data in those artifacts, you don't really have a great way to share it without hard coding it. > One downside with this approach is that multiple people working on it will create different copies. To make it possible to merge different copies of the same file, each data entry has a unique UUID and timestamp. This was the first thing that popped up in my mind: Changes stemming from two sources and reconciling them. I see that you have a statement about how to handle data entry from different sources, but I don't see exactly how those are reconciled? For instance, if two users have a copy of the .capsule and make changes, then want to share their changes with the other, you have two individual .capsules with different data. How do you merge them?
- bashtian 20d ago
  Each document record is saved with UUID and timestamps. When deleting a record the data is removed but the record keeps a tombstone so only the ID remains. For conflicts currently the newest one is used, but there will be a merge like UI in the future to confirm which one to use.
  - srikanthkasa 18d ago
    [dead]
- wwn_se 19d ago
  Git, html+css+svg and data in json.
rc-1140 20d ago
This is a really cool and practical idea! Some of my first professional efforts out of college were writing Python mini-apps with Tkinter to replace "abused" Excel spreadsheets. One of my friends working in sales might benefit from something like this, I'll send it his way. I don't know about the stability/market value of this if you intend to turn this into something that attempts to make money, however. Said friend is currently using stuff like Gemini to generate HTML mini-apps as well; while he's not storing anything in databases, he's able to generate receipts and other things for essentially free.
Jonovono 20d ago
“Capsule.app” is damaged and can’t be opened. You should move it to the Trash.
thesurlydev 20d ago
With the battle of AI versus human agency raging I have a prediction that local-first desktop apps are going to make a comeback. It's nice to see something like this make it easier.
- rglover 20d ago
  I agree and would love to see a shift back to what we had circa ~2009-2010: high quality, desktop and platform-specific apps that you could just pay for once (the best variant for everyone being an app that works indefinitely, but only receives updates if you renew your license every year). The whole shift to SaaS has decimated software quality and has made most tasks a nightmare to complete (or at best, an obstacle course of multiple tools and "upgrades" and other bs).
  - Watchtrail 20d ago
    [flagged]
- dsparkman 20d ago
  I know that I personally have a handful of personal local only apps under development, that in the past I would have reached for a web solution.
- explorigin 20d ago
  In preparation for the upcoming [Android lockdown](https://keepandroidopen.org/ https://keepandroidopen.org/) I've started vibe-coding some PWAs for apps that I like so I can have a webby version of them with no ads and no Google/iOS lock-in. I like this, it feels like a good direction.
- krapp 20d ago
  It's depressing that everyone decided Electron was the final form of all applications and that native apps were dead until AI came along, and if native apps come back it will only be as vibe-coded slop. It's like we've just moved from once circle of hell into another. Also Show HN is supposed to be for posting code that the community can discuss and play with. Plain advertisements and landing pages aren't allowed.
domh 20d ago
I wish there was a way to see the underlying HTML/JS and schema of these container files. Maybe you can on the desktop app? But it would be cool to see what's happening under the hood. Do you have any plans to do merging of two versions of the same app? E.g. I send a todo list to someone, they mark some things as done and send it back to me. Will that merge into my copy if I've added some more items or would it open as a "fresh" app?
- bashtian 20d ago
  Merging works already but is a little bit hidden under the data editor function in the Capsule edit menu. Currently the last record update wins, but a merge UI is planed to do manual conflict resolving.
orliesaurus 20d ago
Is this a durable object? /s
mg 20d ago
> but trying to save data required hosting it somewhere With the File System Access API, webpages nowadays can read and write local files just like desktop applications: https://developer.chrome.com/docs/capabilities/web-apis/file-system-access https://developer.chrome.com/docs/capabilities/web-apis/file... Try this text editor for example: https://googlechromelabs.github.io/text-editor/ https://googlechromelabs.github.io/text-editor/ It works nicely on Desktop and Mobile.
- pspeter3 20d ago
  My dream is that you could write to Google Drive or iCloud Drive transparently too if the browser allows you to
  - jg0r 20d ago
    I believe you are able to connect to a Google Drive account with a purely client side site via google oauth and then using the Google Drive rest api. There was an article in particular that I liked that walked through it. Let me see if I can find it
    - Lord_Zero 20d ago
      Yes but Google OAuth is a nightmare if you want to "publish" your client so that anyone can use it. If only you use it, you can add yourself as a test user. Just know your access token expires super fast and you will have to frequently re-auth. Its crazy annoying.
  - realPubkey 19d ago
    This is possible with RxDB, you can sync from browser to google drive or ms onedrive
- emaro 20d ago
  *In Chrome.
  - simongray 20d ago
nater5000 20d ago
I don't know, this seems like an idea that maybe works in a specific context being generalized past the point of the original idea making sense. If the user needs to download a specific application to run this these web apps, then why not just send them that initial application in the first place? Why jump through the hoops of using Capsule when the same hoops can be jumped through to get to the same endpoint? If this was a near-universally adopted application, then it'd make sense. But it's not, and the closest thing we have to that are browsers... which already do what you're describing? Bundling data with the application makes sense, but is also only appropriate in pretty narrow circumstances. If I'm willing to ship my data with the web app, then I'll just embed the data in the HTML file. If the expectation is that the user will modify this data, then I don't think I'd want to ship it like this.
- pbronez 20d ago
  Seems pretty useful in an enterprise context to me. I see it as an alternative to 10 million vibe coded apps to dockerize and manage. You can put the runtime on everyone’s machine and provide a web version for really collaborative stuff. Bonus points for an intelligent way to manage these stored in OneDrive and other cloud folders. Easy to get corruption on SQLite files stored there.
  - crab_galaxy 20d ago
    It could be useful for us with home labs for the same reasons. Kind of annoying to deploy docker containers for all the services I build that amount to personalized/skinned trello boards.
    - dizzard 20d ago
      Not trying to plug myself, but I’ve been working on a similar project for this exact reason. It doesn’t use special file types. Just HTML and localStorage proxies to sync devices. It’s self-hostable too. I’ve got a bunch of super niche todo lists and personal apps running on my home server with it. https://github.com/momja/Exhibit https://github.com/momja/Exhibit
  - 20d ago
m-p-3 20d ago
It kinda reminds me of MS Access, which ended up being a pain in the butt for IT departments, but also covered a need within some department with limited resources. Really curious to see where this goes. Do you plan to open-source the client, or simply make the file specification open when stabilized?
- bashtian 20d ago
  I'm currently 50/50 on open source the full app vs just the spec. Since I'm currently having a strong idea of what features and functionality is still missing I feel that open-sourcing right now would distract to much in this phase. But maybe when the main features are done it would make sense to have more people looking at and improving it.
  - m-p-3 20d ago
    Do what you feel is best for this project and good luck :)
uneekname 20d ago
Is this project open source?
xyrez 20d ago
This sounds like a Smalltalk image, just without the self-modifying capability, which is what makes this whole idea of code+data in a single file so appealing IMHO.
nzoschke 20d ago
Looks neat. Shuffling artifacts around is more important than ever with all the agentic web sites and apps we are making. Im finding a lot of success embedding metadata and data in SQLite files for music management. Having a spec for a single file with a schema, version, metadata and binary blobs is super easy to shuffle around. Agents crush reading and writing the data and writing tools around the spec. All of a sudden things like backup, sharing and dedupe are snapping into place for my music library. More thoughts here: https://deadca7.com/blog/deadca7-open-music-database-specification https://deadca7.com/blog/deadca7-open-music-database-specifi...
rvz 20d ago
Attackers / Malware Developers: "A document as a web app?, What could possibly go wrong?"
ninininino 20d ago
I'm surprised to not see Pocketbase mentioned in this thread at all. https://pocketbase.io/docs/ https://pocketbase.io/docs/ "PocketBase is an open source backend consisting of embedded database (SQLite) with realtime subscriptions, builtin auth management, convenient dashboard UI and simple REST-ish API. It can be used both as Go framework and as standalone application. The easiest way to get started is to download the prebuilt minimal PocketBase executable"
atikhabib 20d ago
[flagged]
saejox 20d ago
like downloading exe files from the web. but we should invent something to catch bad actors putting bad stuff in them
tombert 20d ago
I remember a million years ago, when I was writing apps with Cordova/Phonegap, I would use Web SQL to do all my storage [1]. This kind of reminds me of that. I always thought that there should be an easy way to export it, but I don't think that ever materialized. [1] https://en.wikipedia.org/wiki/Web_SQL_Database https://en.wikipedia.org/wiki/Web_SQL_Database
JonathanCross 20d ago
[dead]
smy20011 20d ago
Do you plan to open source it? Seems like a proprietary app & spec.
Brajeshwar 20d ago
Personally, you lost me at `.capsule`. I assume this is your format? Now, what happenss when you are not around or I don't have access to you when it is needed most?
starcast2026 20d ago
Sorry I am confused. If you(u1) share a link (html page) with your friend (u2), they fill data/form, then it get saved in u2's desktop. How does u1 see it?
- messh 20d ago
  this is for local apps
veqq 20d ago
Decker works similarly to this (without the SQL-lite, but directly in the single flat html file which can be statically hosted or passed around, and includes an editor for itself!) https://github.com/JohnEarnest/Decker https://github.com/JohnEarnest/Decker
tinyutil 20d ago
[flagged]
writtenone 20d ago
This is proprietary. Yuck
vancekai 20d ago
[dead]
bbstats 20d ago
this is great for the 'make a webapp for me and my family' thing
altern8 20d ago
Looks amazing, I don't know if this is legit or useful feedback, but I navigated away after reading "Generate & update apps using AI". I'm so tired of AI everywhere and everything trying to sell to you because of AI this and AI that. I think that at this point we assume AI will be available if it makes sense for the product, making it a selling point to me is like slapping "No cholesterol!" on lettuce.
manlymuppet 20d ago
Is the file still fairly readable as plain text when opened with any old text editor? Is this asking too much?
annrap1d 20d ago
Is this open source ?
zarrdoz 20d ago
This would be great if it evolved in a universal format/spec/feature supported by all major browsers. Only then you'd have to deal with cross web engine compatibilities. And if capsules need to do something non-trivial then you need to consider all the security aspects of having system, file or network level access. Just like any executable. Otherwise with custom app to run capsules it feels like something that can be vibe coded with electron/nw.js rather easily. But there is something compelling in the idea - there is need for an interactive smart document format that you can share around easily. Kind of like a next gen markdown derivative cross with jupyter notebook where you bundle data, live parametric visualizations, code, audio, video, asciicinema like playback, comments, metadata, file artifacts etc
deleted 20d ago
[deleted]
DarmokTanagra 20d ago
[dead]
4ndrewl 20d ago
It's 1990s Microsoft Access but with AI
taoh 20d ago
[dead]
probablyStimmed 20d ago
I like that there are so many haters who don’t get it or don’t think it’s useful and then there are 5 or so very similar projects in various stages of development listed in the comments. It’s giving “what if I don’t like beans?”
yuedongze 20d ago
We are so back. I remember ActiveX in the old days
francislavoie 20d ago
I've been doing this with bun lately, single file app with built in SQLite. JS runtime which serves the app with SSR, websockets, and all that good stuff. The binary size is not that small, but that's usually worth the convenience.
rupertsworld 20d ago
This reminds me a little bit of https://webtil.es/ https://webtil.es/, which can be either bundled standalone files or hosted, and add a special secure execution context.
andix 20d ago
I really like the idea. It's so easy to create small tools with AI now, but hard to install them as local apps or share them. But I'm missing a few relevant features: 1. syncing data and apps (capsules) between my devices. not necessarily over a single SaaS, but maybe p2p or some existing service 2. I think data and apps should be separated, I might want to share an app with someone else without sharing the data 3. Apps should support updates, install the same app again and just replace the code for the existing app, but keep the data. Also share updates either as a file or publish apps to a repo (just a folder of files on a public http server or github repo) Both keeping data in sync between devices and providing offline capabilities is hard, I know.
- panphora 20d ago
  [flagged]
xori 20d ago
my-bookreport-v2-final-final-done.capsule
shepherdjerred 20d ago
reminds me of https://fzakaria.com/2026/08/23/your-executable-is-a-sqlite-database https://fzakaria.com/2026/08/23/your-executable-is-a-sqlite-...
deleted 20d ago
[deleted]
jayde2767 20d ago
Was Capsule written in Capsule?
nbhankes 20d ago
This is great. My initial thought is to create a zettel for my research projects.
rtpg 20d ago
I feel like this is close to a good idea. What I would want to see is a version of this that lets me write an app that can write to the DB through an API, and then have a google drive-esque "host this for me" thing. A focus on local-first really misses the point IMO. Like sure it's good it can be run locally, but really most people have a distribution problem. Be a distribution solution! The thing I would do involves having the hosting just be available by dropping the capsule into the google drive/dropbox-y thing, and then having it be that you can just copy/paste the file to someone _and it carries over the data and everything by default_. For a lot of people the "thing" is the app + the data. Sometimes you want to decouple them but a lot of times you don't want to. I think it would be very rare for someone to want to share the single-file bundle just without data.
radicalbit 20d ago
i built something similar back in 2013, but it used to keep the persistent state in the url params (obv not a good storage backend), and you would get a super long url to share over facebook haha
rramon 20d ago
Whats the advantage over plain single html files/apps using colocated css and use the browser/web view local storage? Those could be saved as PWAs or not?
ezst 20d ago
For the curious, the note taking app Trilium has a "standalone" mode¹, built on top of OPFS² and sqlite OPFS persistence, such that your notes (~web pages here) are stored in sqlite locally, offline-available, optionally syncing with a remote, while being a pure local web app (after the app assets have been downloaded once). If you want to take your whole personal notes/wiki/pkms for offline access on a device you don't own/have install rights, that's the only way I know. I suspect that OP could have gone this route instead had he known about it? ¹: https://app.triliumnotes.org/ https://app.triliumnotes.org/ ²: https://developer.mozilla.org/en-US/docs/Web/API/File_System_API/Origin_private_file_system https://developer.mozilla.org/en-US/docs/Web/API/File_System... ³: https://sqlite.org/wasm/doc/trunk/persistence.md#opfs https://sqlite.org/wasm/doc/trunk/persistence.md#opfs
- zhynn 19d ago
  I did not know this! What a cool feature.
eliauelkouby 19d ago
[flagged]
flossly 19d ago
I miss from the home page a link to github and/or a description of it's license and/or some code of an actual capsule app (what backend language is used? -- I have no clue and cannot find out) and/or does this bundle Node? While I wish your project success and like the simplicity of Sqlite; I prefer to start with Postgres. PG has many of the benefits (x-platform, free, embeddable, etc) that sqlite has, but also provides an industrial strength db in case you need to scale at some point, or want to use more complicated constructs.
whizzter 19d ago
I was literally thinking of building something similar this summer, one requirement I had however was that it should be runnable/shareable over the web (it's web-tech after all). My use case was storing a family tree with data/app that could be shared, and family members they would be able to add to it and later merge also. Ie, it's a webpage you can dump anywhere, then download/edit locally.
molsongolden 19d ago
Adding to the chorus of “this looks like X old thing”. This reminds me of Clipper/dBase software tools. One of my favorite pieces of software was a tiny program file + flat-file .dbf for storage. Drag and drop the folder to install or share.
- ra 19d ago
  Ah yes that was a whole era of programming for me. It was really fast to ship features... and then came the web!
ferflowhq 19d ago
Love the UI. Simple and clean. Html instead of full app is nice idea. Make online sharing for collaboration edit, but yep need cloud storage.
soltanov 19d ago
I really like this idea. It will be useful for local first users for simple applications. Is it open source? If yes, can you share the link? if not, how can we send templates under our name? are there any template or app marketplace? @bashtian
edwardbonnett 19d ago
could see this being handy for a little game with the save bundled in
MattCruikshank 19d ago
Neat! Another way to achieve something like this is Cosmopolitan C Compiler, Actually Portable Executables. For example, Redbean. (Jart, all of your certs are bad! I can't open your websites any more!) http://justine.lol/ http://justine.lol/ It's a binary that can run on Windows, Mac, Linux, and it is also a zip file. The application can read the zip file and on several systems (not Windows), it can self-modify the zip file. Including hosting SQLite inside the ZIP file.
- zhynn 19d ago
  I have been meaning to use Justine's RedBean to build a "project app" (kind of like what the OP describes, but leaning more towards something like Datasette). It would contain the data, the paper(s), and the UI for interacting with the data (and supporting scripts or R that can be run with other tools). I just like the idea of a portable single-file scientific artifact. (also another call for jart to fix their certs!)
  - MattCruikshank 19d ago
    I'm kind of exhausted... I want to sick Claude on porting tsnet to a C/C++ library that can run in a fat binary Actually Portable Executable. And then I want to use tailscale share / tailscale funnel APEs for... everything... Like... everything. So many things.
deleted 19d ago
[deleted]
cush 19d ago
It seems a bit ridiculous but there’s definitely something here. I have been really enjoying building similar single-file prototypes with agents. They seem to have no trouble dealing with all the code being piled in one big file and you can skip all the complexity, time, and token cost of of bundling.
admiralrohan 19d ago
Interesting concept. Looks like zip replacement. UX improveemnt. I have one concern, can my machine natively read capsule file format? Else no one would open the shared files.
forest_brothers 19d ago
[flagged]
anderspetersson 19d ago
How do I build apps that save data to the .capsule file, beyond the templates?
eternityforest 18d ago
I've always wanted something like this! But I'd want to see some kind of clouds storage sync to actually use it for anything practical. Maybe it could include YJS, with agents taught to use it, and save/load them to Google Docs?
- bashtian 18d ago
  I just added Google Drive support to the Capsule Web app, which supports reading and writing capsule files. More cloud providers and features are planned, along with integration into the desktop app.
  - eternityforest 18d ago
    Very cool!
Studui81Labs 18d ago
[flagged]
mrhcon 18d ago
[flagged]
sago350 18d ago
I’ve been experimenting with Capsule and really like the concept. I confirmed that external REST APIs work from Capsule via fetch(). I’d like to use Capsule as a lightweight/offline client for Claris FileMaker Server, but FileMaker Data API does not support CORS or OPTIONS preflight requests, so a direct request currently fails with TypeError: Load failed. Would you consider providing a native HTTP API through the Capsule/Tauri host, e.g. capsule.http.request()? That would allow: Capsule → Native HTTP → FileMaker Data API without requiring a separate proxy server, while still allowing Capsule to control network access through its permission system. I think this would be useful beyond FileMaker too — for internal/legacy REST APIs, NAS devices, IoT devices, and other local-network APIs without browser-compatible CORS support. The idea of a self-contained Capsule app that works offline, stores data locally, and syncs directly with an existing business system when online is especially interesting to me.
- bashtian 18d ago
  Thank you for providing such a concrete use case, this is exactly why I created Capsule in the first place. I will add support for APIs without CORS in the next version of the app.
Studui81Labs 16d ago
[flagged]
diyzt43bj 16d ago
[flagged]
shamsalom94 16d ago
https://upshot.fyi/ https://upshot.fyi/ solves the storage issue

298 points by bashtian 20d ago

p32929 18d ago

[flagged]

andai 20d ago

That's pretty cool. But who is this for? What problem does it actually solve? How would I know if I need this, vs something else?

bashtian 20d ago
If try to do data management in Excel or need to download an app just to save some recipes, this could be an alternative. For example you can track time and billing with a nice UI without requiring a SaaS subscription. You can try some examples in https://withcapsule.app/preview https://withcapsule.app/preview

lewisjoe 20d ago

This is great. Curious: this requires users to have a host app installed on their machine that can read .capsule file right? Won't that be a point of friction for distribution? Isn't html/css a better distribution mechanism as most computers already have the tech to run them?

bashtian 20d ago
The problem is that you can't save the user data in way that you can click a single file, similar to a Word or Excel file. I you think a about it, a Excel spreadsheet is also just UI + data in a single file.
- paweladamczuk 20d ago
  This is a frustration of mine as well, but I vaguely remember someone showing something on HN where the file could essentially save itself, I think they were using some file APIs for that... sadly I can't find the details anymore. But I keep running into the "HTML file opened locally can't update itself" issue repeatedly now that I build tools for myself with LLM agents.
  - yoz 20d ago
    The File System Access API can do this, and it works in local ("file:///") HTML files, but it's only currently supported in desktop Chromium browsers: https://caniuse.com/native-filesystem-api https://caniuse.com/native-filesystem-api However, every browser will let you download a new version of the HTML file and save it over the old one - yes, even from a local HTML file: const blob = new Blob(['<!DOCTYPE html>\n' + document.documentElement.outerHTML], { type: 'text/html' }); const a = document.createElement('a'); a.href = URL.createObjectURL(blob); a.download = 'mypage.html'; a.click(); ... but you need the user to do this for every update. So we're back to manual "Save" buttons.
    - Jonovono 20d ago
      This is the approach Bento took I believe (similar idea, but just for decks): https://github.com/nyblnet/bento https://github.com/nyblnet/bento. Saw it on HN a few weeks back

pmkary 20d ago

Really really nice

bezko 20d ago

[flagged]

eleventen 20d ago

You can get a cheap approximation of this with chromium browsers + Filesystem API and a PWA manifest for that native-ish feel. AI has reignited my interest in building based 100% on browser native features. https://developer.mozilla.org/en-US/docs/Web/API/File_System_API https://developer.mozilla.org/en-US/docs/Web/API/File_System...

bashtian 20d ago
If you want to distribute apps to many users this would probably be a better solution. The main benefit of Capsule is the personal document like app. You create a capsule, move it to an USB stick, save it in your cloud storage and it's still the same document. Nothing has changed, not the UI, not the data. The document will stay the same.
- ramon156 20d ago
  how is a filesystem supposed to prevent you from doing that?
- al_borland 20d ago
  If it’s web native, anyone can just use it. If it’s a capsule, they first need to download the capsule app to associate the file extension with the OS and have it launch, right? That feels like a big barrier, almost like a Java runtime.
  - eleventen 20d ago
    In defense of capsule, the Filesystem API is janky and has kind of shit UX. Less sophisticated users would probably prefer the UX of a purpose built tool. I prefer worse UX for the sake of standards and zero install, but many people would prefer the opposite. I don't think Capsule is intended for the HN crowd.

zackify 20d ago

love this idea!

gadders 20d ago

>>Capsule packs your entire app — UI, data, and everything — into a single portable .capsule file. I'm having Lotus Notes flashbacks.

p2detar 20d ago
Indeed. But Lotus Notes actually had the design and data stored independent of one another and you had database templates. You could update your design without breaking the data, or even have entirely different design that works with the existing data model. This capsule thing seems to store the design itself within the database, which is odd to me. I guess I don't get it at 100%.
- gadders 19d ago
  Yeah, it's not an exact match. But I could email you a lotus notes nsf file and you could open it in your Notes client and have the data and the application in front of you.

dgf18 20d ago

Many big companies are starting now to test agentic coding to automate business processes. This could be a nice tool to distribute apps for workflows that aren't big enough to justify the operational overhed of maintaining a traditional web app backend. Nice!

m-p-3 20d ago
This sounds like the modern take on MS Access.

lolakutty 20d ago

What is wrong with using IndexedDB?

bashtian 20d ago
For saving data in the capsule file it would create complexity regarding migration handling when updating the HTML file to add a field to a form for example. Keeping the data schemaless makes it also easier for merging data or importing data from a CSV.
- lolakutty 20d ago
  Doesn't indexedDB have builtin migration mechanism? >Keeping the data schemaless makes it also easier for merging data or importing data from a CSV. Not sure how it makes easier. There is always an implicit or explicit schema. IMHO explicit is often better.

fdeth 20d ago

So, let’s do Visual Basic again, but this time with LLMs and web stuff.

blamestross 20d ago

Seems very "packable into a standalone binary" but doesn't seem like that is a planned use case.

bashtian 20d ago
The problem would be cross-platform support. In the end the capsule file is the standalone binary similar to a PDF or a Word document, you only need the viewer app to open any capsule file.
- blamestross 20d ago
  you can trivially bake X binaries if you have the viewer app for each platform. This is the normal way to distribute software for cross-platform support. I might just be hyper-defensive to any sort of vendor lock-in like a "viewer app".

tonymet 20d ago

is the idea this would be hosted or run locally (like Electron)?

bashtian 20d ago
This is for local document like apps. Tauri is actually using the OS webview instead of bundling Chromium like Electron. That's why the download is only 10MB for Mac.
- tonymet 20d ago
  i like that idea. Anything that improves native OS UI, responsiveness (120hz) and reduces resources is a good idea.

redog 20d ago

This seems ripe for an injection attack. Can it be inspected before running?

deleted 20d ago
[deleted]

jawns 20d ago

My take: If your app needs to update and preserve state (using SQLite or any other DB), it is probably not something you want to pass around as a bundled file. Or at least, it's extremely limiting, compared with hosting it somewhere on the web, which is not that hard to do these days. Think of the workflow: Any time the state changes, you need to email a new Capsule file to whoever else is using the app. And one would think the state would change at least occasionally, because otherwise there's little reason to use a DB. Alternatively, you can just host it on the web, the DB state dynamically updates, and it's automatically available to anyone with app access. Isn't that a lot simpler?

Reviving1514 20d ago
Why not on a shared drive like dropbox? Concurrent editing wouldn't work, though.
- teraflop 20d ago
  Beyond "not working", concurrent editing is likely to silently lose data, or corrupt data, or possibly just fill up your drive with lots of "conflicted copies" that you have to manually reconcile.
  - dizzard 20d ago
    When I read about this project, it doesn’t seem like concurrency is much of a concern. I think it’s _supposed_ to be treated like sharing a document with someone else. If a capsule is a recipe, like in one of the examples, that’s pretty cool. If a capsule is a recipe _manager_, then I think it would get messy.
latexr 20d ago
> Isn't that a lot simpler? You’re glossing over the recurring cost and annoyance of dealing with the hosting and having to secure the data. This way you just share and it’s local. Sure, if you have to share data between people, your points are valid. But this seems like a way to build apps geared for individual users, like a notes or recipes app.

tamimio 20d ago

New way to deliver viruses just dropped! Great idea but it can be abused for sure.

bashtian 20d ago
The HTML files does not have any permission to access anything on the file system. Ideally the whole app will be running inside a sandbox on desktop, for mobile apps this will be the default anyway.

thederf 20d ago

I've been working on this exact idea, with sqlar as the "format specification". Works in the browser, and desktop + Android using Tauri. https://github.com/JoshTheDerf/uapp https://github.com/JoshTheDerf/uapp Demo apps and games: https://thederf.com/uapp/demo/ https://thederf.com/uapp/demo/

windsurfer 20d ago
FYI requests from your demo are being blocked by CORS in Firefox and it never loads.
- thederf 20d ago
  Thanks for the heads up! Fixed now, was a bug in the service worker.
deleted 20d ago
[deleted]

sigmonsays 20d ago

if state is best shared, why keep it w/ the code? You're gonna end up having to build a complex state sync system to a central DB anyways...

olaulailadila 20d ago

An idea for a killer feature: Make it so that auhors can expose their capsules to the internet, and the people whoe wants to use them(lets call them users) can type the name(lets call it address) of the caplsue into the app, and your program will pull that capsule in the the users device..

derpyzza 20d ago
wow, that sounds revolutionary.
ligarota 20d ago
Hear me out. Here is the name PWA : Probably Web Again
saejox 20d ago
nice. we should call it web, like spiders' web all connected.

dzink 20d ago

Looks useful, but the Mac download shows "“Capsule” is damaged and can’t be opened. You should eject the disk image." and then you realize it could be ripe for malicious payloads as well.

xd1936 20d ago

"No cloud. No accounts. Just share it." close tab

j-pb 20d ago
yes yes we get it, you don't like AI ...
mionhe 20d ago
Can you elaborate a little?
- al_borland 20d ago
  It reads like the whole thing was vibe coded and 0 work was done beyond what the AI spit out.
derpyzza 20d ago
well that's a first

razerbeans 20d ago

I love this idea! One of the fallouts from widespread AI adoption that I've seen: They're very good at creating visual artifacts, but if you ever have to provide data in those artifacts, you don't really have a great way to share it without hard coding it. > One downside with this approach is that multiple people working on it will create different copies. To make it possible to merge different copies of the same file, each data entry has a unique UUID and timestamp. This was the first thing that popped up in my mind: Changes stemming from two sources and reconciling them. I see that you have a statement about how to handle data entry from different sources, but I don't see exactly how those are reconciled? For instance, if two users have a copy of the .capsule and make changes, then want to share their changes with the other, you have two individual .capsules with different data. How do you merge them?

bashtian 20d ago
Each document record is saved with UUID and timestamps. When deleting a record the data is removed but the record keeps a tombstone so only the ID remains. For conflicts currently the newest one is used, but there will be a merge like UI in the future to confirm which one to use.
- srikanthkasa 18d ago
  [dead]
wwn_se 19d ago
Git, html+css+svg and data in json.

rc-1140 20d ago

This is a really cool and practical idea! Some of my first professional efforts out of college were writing Python mini-apps with Tkinter to replace "abused" Excel spreadsheets. One of my friends working in sales might benefit from something like this, I'll send it his way. I don't know about the stability/market value of this if you intend to turn this into something that attempts to make money, however. Said friend is currently using stuff like Gemini to generate HTML mini-apps as well; while he's not storing anything in databases, he's able to generate receipts and other things for essentially free.

Jonovono 20d ago

“Capsule.app” is damaged and can’t be opened. You should move it to the Trash.

thesurlydev 20d ago

With the battle of AI versus human agency raging I have a prediction that local-first desktop apps are going to make a comeback. It's nice to see something like this make it easier.

rglover 20d ago
I agree and would love to see a shift back to what we had circa ~2009-2010: high quality, desktop and platform-specific apps that you could just pay for once (the best variant for everyone being an app that works indefinitely, but only receives updates if you renew your license every year). The whole shift to SaaS has decimated software quality and has made most tasks a nightmare to complete (or at best, an obstacle course of multiple tools and "upgrades" and other bs).
- Watchtrail 20d ago
  [flagged]
dsparkman 20d ago
I know that I personally have a handful of personal local only apps under development, that in the past I would have reached for a web solution.
explorigin 20d ago
In preparation for the upcoming [Android lockdown](https://keepandroidopen.org/ https://keepandroidopen.org/) I've started vibe-coding some PWAs for apps that I like so I can have a webby version of them with no ads and no Google/iOS lock-in. I like this, it feels like a good direction.
krapp 20d ago
It's depressing that everyone decided Electron was the final form of all applications and that native apps were dead until AI came along, and if native apps come back it will only be as vibe-coded slop. It's like we've just moved from once circle of hell into another. Also Show HN is supposed to be for posting code that the community can discuss and play with. Plain advertisements and landing pages aren't allowed.

domh 20d ago

I wish there was a way to see the underlying HTML/JS and schema of these container files. Maybe you can on the desktop app? But it would be cool to see what's happening under the hood. Do you have any plans to do merging of two versions of the same app? E.g. I send a todo list to someone, they mark some things as done and send it back to me. Will that merge into my copy if I've added some more items or would it open as a "fresh" app?

bashtian 20d ago
Merging works already but is a little bit hidden under the data editor function in the Capsule edit menu. Currently the last record update wins, but a merge UI is planed to do manual conflict resolving.

orliesaurus 20d ago

Is this a durable object? /s

mg 20d ago

> but trying to save data required hosting it somewhere With the File System Access API, webpages nowadays can read and write local files just like desktop applications: https://developer.chrome.com/docs/capabilities/web-apis/file-system-access https://developer.chrome.com/docs/capabilities/web-apis/file... Try this text editor for example: https://googlechromelabs.github.io/text-editor/ https://googlechromelabs.github.io/text-editor/ It works nicely on Desktop and Mobile.

pspeter3 20d ago
My dream is that you could write to Google Drive or iCloud Drive transparently too if the browser allows you to
- jg0r 20d ago
  I believe you are able to connect to a Google Drive account with a purely client side site via google oauth and then using the Google Drive rest api. There was an article in particular that I liked that walked through it. Let me see if I can find it
  - Lord_Zero 20d ago
    Yes but Google OAuth is a nightmare if you want to "publish" your client so that anyone can use it. If only you use it, you can add yourself as a test user. Just know your access token expires super fast and you will have to frequently re-auth. Its crazy annoying.
- realPubkey 19d ago
  This is possible with RxDB, you can sync from browser to google drive or ms onedrive
emaro 20d ago
*In Chrome.
- simongray 20d ago

nater5000 20d ago

I don't know, this seems like an idea that maybe works in a specific context being generalized past the point of the original idea making sense. If the user needs to download a specific application to run this these web apps, then why not just send them that initial application in the first place? Why jump through the hoops of using Capsule when the same hoops can be jumped through to get to the same endpoint? If this was a near-universally adopted application, then it'd make sense. But it's not, and the closest thing we have to that are browsers... which already do what you're describing? Bundling data with the application makes sense, but is also only appropriate in pretty narrow circumstances. If I'm willing to ship my data with the web app, then I'll just embed the data in the HTML file. If the expectation is that the user will modify this data, then I don't think I'd want to ship it like this.

pbronez 20d ago
Seems pretty useful in an enterprise context to me. I see it as an alternative to 10 million vibe coded apps to dockerize and manage. You can put the runtime on everyone’s machine and provide a web version for really collaborative stuff. Bonus points for an intelligent way to manage these stored in OneDrive and other cloud folders. Easy to get corruption on SQLite files stored there.
- crab_galaxy 20d ago
  It could be useful for us with home labs for the same reasons. Kind of annoying to deploy docker containers for all the services I build that amount to personalized/skinned trello boards.
  - dizzard 20d ago
    Not trying to plug myself, but I’ve been working on a similar project for this exact reason. It doesn’t use special file types. Just HTML and localStorage proxies to sync devices. It’s self-hostable too. I’ve got a bunch of super niche todo lists and personal apps running on my home server with it. https://github.com/momja/Exhibit https://github.com/momja/Exhibit
- 20d ago

m-p-3 20d ago

It kinda reminds me of MS Access, which ended up being a pain in the butt for IT departments, but also covered a need within some department with limited resources. Really curious to see where this goes. Do you plan to open-source the client, or simply make the file specification open when stabilized?

bashtian 20d ago
I'm currently 50/50 on open source the full app vs just the spec. Since I'm currently having a strong idea of what features and functionality is still missing I feel that open-sourcing right now would distract to much in this phase. But maybe when the main features are done it would make sense to have more people looking at and improving it.
- m-p-3 20d ago
  Do what you feel is best for this project and good luck :)

uneekname 20d ago

Is this project open source?

xyrez 20d ago

This sounds like a Smalltalk image, just without the self-modifying capability, which is what makes this whole idea of code+data in a single file so appealing IMHO.

nzoschke 20d ago

Looks neat. Shuffling artifacts around is more important than ever with all the agentic web sites and apps we are making. Im finding a lot of success embedding metadata and data in SQLite files for music management. Having a spec for a single file with a schema, version, metadata and binary blobs is super easy to shuffle around. Agents crush reading and writing the data and writing tools around the spec. All of a sudden things like backup, sharing and dedupe are snapping into place for my music library. More thoughts here: https://deadca7.com/blog/deadca7-open-music-database-specification https://deadca7.com/blog/deadca7-open-music-database-specifi...

rvz 20d ago

Attackers / Malware Developers: "A document as a web app?, What could possibly go wrong?"

ninininino 20d ago

I'm surprised to not see Pocketbase mentioned in this thread at all. https://pocketbase.io/docs/ https://pocketbase.io/docs/ "PocketBase is an open source backend consisting of embedded database (SQLite) with realtime subscriptions, builtin auth management, convenient dashboard UI and simple REST-ish API. It can be used both as Go framework and as standalone application. The easiest way to get started is to download the prebuilt minimal PocketBase executable"

atikhabib 20d ago

[flagged]

saejox 20d ago

like downloading exe files from the web. but we should invent something to catch bad actors putting bad stuff in them

tombert 20d ago

I remember a million years ago, when I was writing apps with Cordova/Phonegap, I would use Web SQL to do all my storage [1]. This kind of reminds me of that. I always thought that there should be an easy way to export it, but I don't think that ever materialized. [1] https://en.wikipedia.org/wiki/Web_SQL_Database https://en.wikipedia.org/wiki/Web_SQL_Database

JonathanCross 20d ago

[dead]

smy20011 20d ago

Do you plan to open source it? Seems like a proprietary app & spec.

Brajeshwar 20d ago

Personally, you lost me at `.capsule`. I assume this is your format? Now, what happenss when you are not around or I don't have access to you when it is needed most?

starcast2026 20d ago

Sorry I am confused. If you(u1) share a link (html page) with your friend (u2), they fill data/form, then it get saved in u2's desktop. How does u1 see it?

messh 20d ago
this is for local apps

veqq 20d ago

Decker works similarly to this (without the SQL-lite, but directly in the single flat html file which can be statically hosted or passed around, and includes an editor for itself!) https://github.com/JohnEarnest/Decker https://github.com/JohnEarnest/Decker

tinyutil 20d ago

[flagged]

writtenone 20d ago

This is proprietary. Yuck

vancekai 20d ago

[dead]

bbstats 20d ago

this is great for the 'make a webapp for me and my family' thing

altern8 20d ago

Looks amazing, I don't know if this is legit or useful feedback, but I navigated away after reading "Generate & update apps using AI". I'm so tired of AI everywhere and everything trying to sell to you because of AI this and AI that. I think that at this point we assume AI will be available if it makes sense for the product, making it a selling point to me is like slapping "No cholesterol!" on lettuce.

manlymuppet 20d ago

Is the file still fairly readable as plain text when opened with any old text editor? Is this asking too much?

annrap1d 20d ago

Is this open source ?

zarrdoz 20d ago

This would be great if it evolved in a universal format/spec/feature supported by all major browsers. Only then you'd have to deal with cross web engine compatibilities. And if capsules need to do something non-trivial then you need to consider all the security aspects of having system, file or network level access. Just like any executable. Otherwise with custom app to run capsules it feels like something that can be vibe coded with electron/nw.js rather easily. But there is something compelling in the idea - there is need for an interactive smart document format that you can share around easily. Kind of like a next gen markdown derivative cross with jupyter notebook where you bundle data, live parametric visualizations, code, audio, video, asciicinema like playback, comments, metadata, file artifacts etc

deleted 20d ago

[deleted]

DarmokTanagra 20d ago

[dead]

4ndrewl 20d ago

It's 1990s Microsoft Access but with AI

taoh 20d ago

[dead]

probablyStimmed 20d ago

I like that there are so many haters who don’t get it or don’t think it’s useful and then there are 5 or so very similar projects in various stages of development listed in the comments. It’s giving “what if I don’t like beans?”

yuedongze 20d ago

We are so back. I remember ActiveX in the old days

francislavoie 20d ago

I've been doing this with bun lately, single file app with built in SQLite. JS runtime which serves the app with SSR, websockets, and all that good stuff. The binary size is not that small, but that's usually worth the convenience.

rupertsworld 20d ago

This reminds me a little bit of https://webtil.es/ https://webtil.es/, which can be either bundled standalone files or hosted, and add a special secure execution context.

andix 20d ago

I really like the idea. It's so easy to create small tools with AI now, but hard to install them as local apps or share them. But I'm missing a few relevant features: 1. syncing data and apps (capsules) between my devices. not necessarily over a single SaaS, but maybe p2p or some existing service 2. I think data and apps should be separated, I might want to share an app with someone else without sharing the data 3. Apps should support updates, install the same app again and just replace the code for the existing app, but keep the data. Also share updates either as a file or publish apps to a repo (just a folder of files on a public http server or github repo) Both keeping data in sync between devices and providing offline capabilities is hard, I know.

panphora 20d ago
[flagged]

xori 20d ago

my-bookreport-v2-final-final-done.capsule

shepherdjerred 20d ago

reminds me of https://fzakaria.com/2026/08/23/your-executable-is-a-sqlite-database https://fzakaria.com/2026/08/23/your-executable-is-a-sqlite-...

deleted 20d ago

[deleted]

jayde2767 20d ago

Was Capsule written in Capsule?

nbhankes 20d ago

This is great. My initial thought is to create a zettel for my research projects.

rtpg 20d ago

I feel like this is close to a good idea. What I would want to see is a version of this that lets me write an app that can write to the DB through an API, and then have a google drive-esque "host this for me" thing. A focus on local-first really misses the point IMO. Like sure it's good it can be run locally, but really most people have a distribution problem. Be a distribution solution! The thing I would do involves having the hosting just be available by dropping the capsule into the google drive/dropbox-y thing, and then having it be that you can just copy/paste the file to someone _and it carries over the data and everything by default_. For a lot of people the "thing" is the app + the data. Sometimes you want to decouple them but a lot of times you don't want to. I think it would be very rare for someone to want to share the single-file bundle just without data.

radicalbit 20d ago

i built something similar back in 2013, but it used to keep the persistent state in the url params (obv not a good storage backend), and you would get a super long url to share over facebook haha

rramon 20d ago

Whats the advantage over plain single html files/apps using colocated css and use the browser/web view local storage? Those could be saved as PWAs or not?

ezst 20d ago

For the curious, the note taking app Trilium has a "standalone" mode¹, built on top of OPFS² and sqlite OPFS persistence, such that your notes (~web pages here) are stored in sqlite locally, offline-available, optionally syncing with a remote, while being a pure local web app (after the app assets have been downloaded once). If you want to take your whole personal notes/wiki/pkms for offline access on a device you don't own/have install rights, that's the only way I know. I suspect that OP could have gone this route instead had he known about it? ¹: https://app.triliumnotes.org/ https://app.triliumnotes.org/ ²: https://developer.mozilla.org/en-US/docs/Web/API/File_System_API/Origin_private_file_system https://developer.mozilla.org/en-US/docs/Web/API/File_System... ³: https://sqlite.org/wasm/doc/trunk/persistence.md#opfs https://sqlite.org/wasm/doc/trunk/persistence.md#opfs

zhynn 19d ago
I did not know this! What a cool feature.

eliauelkouby 19d ago

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flossly 19d ago

I miss from the home page a link to github and/or a description of it's license and/or some code of an actual capsule app (what backend language is used? -- I have no clue and cannot find out) and/or does this bundle Node? While I wish your project success and like the simplicity of Sqlite; I prefer to start with Postgres. PG has many of the benefits (x-platform, free, embeddable, etc) that sqlite has, but also provides an industrial strength db in case you need to scale at some point, or want to use more complicated constructs.

whizzter 19d ago

I was literally thinking of building something similar this summer, one requirement I had however was that it should be runnable/shareable over the web (it's web-tech after all). My use case was storing a family tree with data/app that could be shared, and family members they would be able to add to it and later merge also. Ie, it's a webpage you can dump anywhere, then download/edit locally.

molsongolden 19d ago

Adding to the chorus of “this looks like X old thing”. This reminds me of Clipper/dBase software tools. One of my favorite pieces of software was a tiny program file + flat-file .dbf for storage. Drag and drop the folder to install or share.

ra 19d ago
Ah yes that was a whole era of programming for me. It was really fast to ship features... and then came the web!

ferflowhq 19d ago

Love the UI. Simple and clean. Html instead of full app is nice idea. Make online sharing for collaboration edit, but yep need cloud storage.

soltanov 19d ago

I really like this idea. It will be useful for local first users for simple applications. Is it open source? If yes, can you share the link? if not, how can we send templates under our name? are there any template or app marketplace? @bashtian

edwardbonnett 19d ago

could see this being handy for a little game with the save bundled in

MattCruikshank 19d ago

Neat! Another way to achieve something like this is Cosmopolitan C Compiler, Actually Portable Executables. For example, Redbean. (Jart, all of your certs are bad! I can't open your websites any more!) http://justine.lol/ http://justine.lol/ It's a binary that can run on Windows, Mac, Linux, and it is also a zip file. The application can read the zip file and on several systems (not Windows), it can self-modify the zip file. Including hosting SQLite inside the ZIP file.

zhynn 19d ago
I have been meaning to use Justine's RedBean to build a "project app" (kind of like what the OP describes, but leaning more towards something like Datasette). It would contain the data, the paper(s), and the UI for interacting with the data (and supporting scripts or R that can be run with other tools). I just like the idea of a portable single-file scientific artifact. (also another call for jart to fix their certs!)
- MattCruikshank 19d ago
  I'm kind of exhausted... I want to sick Claude on porting tsnet to a C/C++ library that can run in a fat binary Actually Portable Executable. And then I want to use tailscale share / tailscale funnel APEs for... everything... Like... everything. So many things.

deleted 19d ago

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cush 19d ago

It seems a bit ridiculous but there’s definitely something here. I have been really enjoying building similar single-file prototypes with agents. They seem to have no trouble dealing with all the code being piled in one big file and you can skip all the complexity, time, and token cost of of bundling.

admiralrohan 19d ago

Interesting concept. Looks like zip replacement. UX improveemnt. I have one concern, can my machine natively read capsule file format? Else no one would open the shared files.

forest_brothers 19d ago

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anderspetersson 19d ago

How do I build apps that save data to the .capsule file, beyond the templates?

eternityforest 18d ago

I've always wanted something like this! But I'd want to see some kind of clouds storage sync to actually use it for anything practical. Maybe it could include YJS, with agents taught to use it, and save/load them to Google Docs?

bashtian 18d ago
I just added Google Drive support to the Capsule Web app, which supports reading and writing capsule files. More cloud providers and features are planned, along with integration into the desktop app.
- eternityforest 18d ago
  Very cool!

Studui81Labs 18d ago

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mrhcon 18d ago

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sago350 18d ago

I’ve been experimenting with Capsule and really like the concept. I confirmed that external REST APIs work from Capsule via fetch(). I’d like to use Capsule as a lightweight/offline client for Claris FileMaker Server, but FileMaker Data API does not support CORS or OPTIONS preflight requests, so a direct request currently fails with TypeError: Load failed. Would you consider providing a native HTTP API through the Capsule/Tauri host, e.g. capsule.http.request()? That would allow: Capsule → Native HTTP → FileMaker Data API without requiring a separate proxy server, while still allowing Capsule to control network access through its permission system. I think this would be useful beyond FileMaker too — for internal/legacy REST APIs, NAS devices, IoT devices, and other local-network APIs without browser-compatible CORS support. The idea of a self-contained Capsule app that works offline, stores data locally, and syncs directly with an existing business system when online is especially interesting to me.

bashtian 18d ago
Thank you for providing such a concrete use case, this is exactly why I created Capsule in the first place. I will add support for APIs without CORS in the next version of the app.

Studui81Labs 16d ago

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diyzt43bj 16d ago

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shamsalom94 16d ago

https://upshot.fyi/ https://upshot.fyi/ solves the storage issue