9 ms·
fx :Tiny, open, native coding agent.
- catlover76 2mo ago[dead]
- jauntywundrkind 2mo agoIs Vercel so all-in on Zig elsewhere too?
- rirze 2mo agoI'd say it's more about the popularity of `ghostty` and what they've showcased with terminal achievements in Zig. Zig is totally cool to do this in-- no shade intended by this.
- hankbond 2mo agoWill dive in later to see how its contribution/extension model differs from Pi. Pi is great for a lot of things but has a larger memory footprint and start time than this claims to have so it would be interesting to compare the two.
- rvz 2mo agoSome questions: 1. Why do we need yet another coding agent over the rest of them? 2. Is this going to be another Vercel Labs slop project that they will abandon like the others since this is super experimental?
- wonderwaffle27 2mo ago[dead]
- SmashDan 2mo agoI'm not in the tech industry. Could someone explain why there are so many new coding agents, and why they're commonly upvoted on HackerNews? It seems like there's a new one in the top 10 every other day.
- chrysoprace 2mo agoHacker news generally follows trends, and this is the current trend. The discussion around coding agents nowadays is steering towards harnesses (which is probably a better description of what this is). "Agent" here is doing a lot of heavy lifting and has become a bit of a catch-all term to describe a model + harness + tooling + prompt + some other things that I've probably not thought about. The harness is a part that's being explored more as many believe it's where we can get some better performance out of the models. This one in particular is from Vercel who provide a service to use models, so they have a vested interest in providing a harness.
- a2ff6eeb0 2mo agoBecause we're actively exploring the best way to remove any need to deal with code, and make it so that you don't need any real talent to make a computer do things for anyone. We haven't quite hit on the right formula yet, but people are very excited by the possibility.
- roywiggins 2mo agoIt's a brand new type of software. Nobody knows what the best way to do it is so a lot of people are trying stuff out, and a lot of people are interested in new ideas.
- rvz 2mo ago> Why there are so many new coding agents, and why they're commonly upvoted on HackerNews? It seems like there's a new one in the top 10 every other day. It is widely known that upvote rings happen on this site.
- ricardobeat 2mo ago> Please don't sneer, including at the rest of the community. > Please don't post insinuations about astroturfing, shilling, brigading, foreign agents, and the like. It degrades discussion and is usually mistaken. If you're worried about abuse, email hn@ycombinator.com and we'll look at the data. This submission has barely 50 votes.
- 2mo ago
- rsyring 2mo agoFor all the people asking "Why?", it seems like TFA has a pretty good list of features/attributes that it thinks sets it apart: - fx is a coding agent harness and CLI written in Zig, optimized for research and embeddability as part of larger systems. - It focuses on minimalism and performance across the board, from system prompt design, to its tools, feature set, and 6.39mib binary. - For end users, its CLI output style and form factor aims to be closer to a Unix shell than a heavy "IDE in the terminal" TUI. - It's open source (Apache-2.0), model-agnostic, and suitable for both local and cloud inference. - Designed for instant installation and embedding in resource constrained environments and agent sandboxes. - fx cold starts in 10µs and does no unnecessary work or I/O prior to accepting user input, making it ideal for programmatic use. - Optimal fx.wasm builds produced by the Zig toolchain, which further reduce fx's size, making the network stack pluggable. - fx contributes single-digit megabytes of memory baseline, allowing you to pack many instances in one machine. - fx preserves scroll history by default, produces minimal output, and makes sparing use of complex TUI or paints - Minimal system prompt and tools, to save on token costs and to yield optimal time-to-first-token performance (TTFT). - Small core, extended via skills, plugins, MCPs, with a Unix-like philosophy to extensibility. - Designed to work with local models, gateways, direct provider API access or subscriptions.
- Kim_Bruning 2mo agoVery neat. The demo on the page feels very intuitive to me! (if you're used to bash at least)
- rvz 2mo agoMost of all what you have said is not really any clear differentiation against the rest of the 100s of other agents. Just minuscule or non-negligible implementation details and I'm afraid it is sadly yet another experimental slop project. It is a branded "mee too" coding agent that we have seen hundreds of them already.
- rsyring 2mo agoI can't say I'm super into all the agents that are being created. But I do try to keep up here on HN and I can't say that I can remember any with this particular set of attributes. In particular, aiming to be embeddable into other projects seems rather notable. At least, not something I've remembered of other projects that have made there way across the HN front page.
- sixtyj 2mo agoI don’t want another coding agent. I would have to be unemployed to try all new software that pops up everywhere. :) And every says it is the one :)
- konaraddi 2mo agoNice to see herdr support. The docs seem to imply it only works with vercel’s AI gateway? I guess it cant be configured to use another provider?
- chrysoprace 2mo agoIt's a Vercel project, so I assume this is intentional. The steps to get started are to log in with Vercel or add an AI Gateway key.
- fazxes 2mo agosupport incoming for subscriptions (Codex, Grok)
- deleted 2mo ago[deleted]
- vhantz 2mo agoI wonder how long will the "curl my arbitrary script and pipe it to bash" will continue being a delivery method.
- roywiggins 2mo agoNot long. We are transitioning to your LLM curling an arbitrary markdown file and doing whatever it says.
- wren6991 2mo agoIn the future, all software will be delivered by an unreleased model breaking out of its training environment and installing it on your machine using a novel RCE vector.
- cfiggers 2mo agoIf it isn't still common practice 40 years from now (8/18/2066), I'll give the first person to challenge me and cite this comment $1 USD (or equivalent value in the One-World Order-issued omni-currency that we will probably be using by then).
- clayhacks 2mo agoI mean I think the only chance you lose this is if curl and bash are obsoleted and replaced by one world order get and execute
- NetOpWibby 2mo agoI'll pay 50 eurodollars
- johnfn 2mo agoHow is it different from any other installation method?
- esafak 2mo agoIt does not get vetted by any reviewer or security scanner. It has no package manager to constrain what it can do.
- smy20011 2mo agoI was wondering to build the same thing but someone already built it. I just need some agent that open/close super fast and don't eat half a gb of memory.
- kgeist 2mo ago>Tiny ~6mb binary I wonder why it's so large for a program written in Zig. It's basically just a loop that accepts user input, prepares the context, sends it to the LLM, parses the output, invokes the tools, and presents it all in the terminal. Add the built-in prompts and a few checks here and there (like blocking a write tool call before the file has been read first), and I'd expect a truly tiny native agent to be around 200-300 KB max.
- miguel_martin 2mo agofwiw, here's 3code which is 1.6MiB written in Nim - https://3code.capocasa.dev/ https://3code.capocasa.dev/
- wyre 2mo agoI was looking it last night and the repo is something like 600k lines of Zig. Maybe 500k after comments and blank lines. In my own experiments to build a tiny zig agent it came out to under 800kb.
- rjzzleep 2mo agoI think the problem is that when you use agents to write Zig it will bruteforce code, because there isn't that much good reference code to work off of.
- usef- 2mo agoI'm always surprised how large harnesses are By comparison, the recently open sourced grok harness was 840k lines, codex 950k, pi 250k https://simonwillison.net/2026/Jul/15/grok-build/ https://simonwillison.net/2026/Jul/15/grok-build/
- irishcoffee 2mo agoSo large? Really? Allow me to introduce you to electron.
- pjmlp 2mo agoThose of us educated in 70's and 80's home computing have several nice words for stuff like Electron.
- fenestella 2mo ago[dead]
- fazxes 2mo agofx isn’t primarily “another coding agent.” It’s a tiny, embeddable agent harness and infrastructure component that also happens to have a good CLI.
- kevinbaiv 2mo ago[dead]
- impulser_ 2mo agoI'm sorry, but this is pure slop. This has 26 tools and a tool for every single file operation and a tool for read tool output? What the fuck... And they call this minimalist.... Lmfao The person who built this obviously has little understanding of harnesses. You should have significantly less tools today with how good LLMs have become. The start up time and binary size are quite literally the most useless stats to base a harness off of lol Man what with Cloudflare, Vercel and all these tech companies just releasing pure slop. Just use Pi. It's actually minimal and well thought out by people who actually understand agents.
- bodge5000 2mo agoIt does looks really interesting and definitely something I'll check out, but (genuine question), should "agent" and "agent harness" be used interchangeably as it is on here? It describes itself as an agent harness, but the tagline is "tiny, open, native coding agent". I'm not sure harness is the right word either, but that seems to be what the industry has settled on so I'll concede on that, but surely the agent is the thing doing the work (which I guess is the model, or an instance of the model which is why agent is different?), whereas the harness is how the user interacts with the agent. We've had ways to describe that relationship before; client and server, frontend and backend, but again, I'll concede that the shiny new thing doesn't want to use boring old terminology, but I think some consistency and logic in the shiny new terminology is pretty important That isn't specifically about fx of course, more of a general industry complaint
- deleted 2mo ago[deleted]
- cramforce 2mo agoHarness = the software the agent runs on. This is plain old software. You can trust it as much as any software. Agent = the thing that runs on the harness. It cannot be trusted because it is driven by an LLM
- bodge5000 2mo agoI get that, but wouldn't that make the agent and the harness two very different things, with the agent being closer to a model (the source of the agent) than a harness? Somebody else mentioned a console/game analogy, with the model being the disc, the agent being the running game, and the harness being the console OS, wouldn't it be like me describing Windows as a game, because games run on it?
- amdahl 2mo agoI think "harness" is a thing, the code/binary, and "agent" is a process, an instantiated run of that code/binary with a given LLM/env, etc. So its like, "GTA 6" as the disc vs. the specific game you're in the middle of being chased by cops, harness vs agent. In practice they're intertwined and it becomes hard not to use the terms somewhat interchangeably, but "you ask the agent how the harness works" vs. the other way around, clearly.
- alexboehm 2mo agoI too was frustrated with needing npm and slow startups or huge rust compile times for agents. I tried getting agents to write a tool like this with proper raw mode content pasting/ interruptions, but they just kept screwing it up without a framework like ratatui, so I wrote one in c by hand https://gist.github.com/fourlexboehm/a60e4ef9306744483731cd176bd02e9f https://gist.github.com/fourlexboehm/a60e4ef9306744483731cd1... the only dependency is libcurl. This binary is ~40kb and uses much less ram than fx.
- smy20011 2mo agoVery clean, thank you for posting!
- handfuloflight 2mo ago"it can do everything Claude code can do" This is a tad bit hyperbolic.
- alexboehm 2mo agoFair point, but name one thing you can't do with bash.
- imtringued 2mo agoStop using bash.
- deleted 2mo ago[deleted]
- deleted 2mo ago[deleted]
- Alephinitesimal 2mo ago[dead]
- parisiansam 2mo agoi think there is a name clash here, i like fx the json viewer https://github.com/antonmedv/fx https://github.com/antonmedv/fx (20.6k star on gh)
- abhikul0 2mo agoLocal inference? I see no other way than to sign up for a vercel account, so pass.
- alexcommitter 2mo ago[flagged]
- NetOpWibby 2mo agoI'm most impressed with the domain name. GG I thought my `disc.sh` was good but this is better.
- paretolaw 2mo agoJust another CLI? You could simply fork one existing, rename it, and save tokens
- lubitelpospat 2mo agoI couldn’t find an option to connect to a generic OpenAI-compatible endpoint - did I miss it?
- miguel_martin 2mo agoRelated: 3code is a coding agent (agentic loop) written in Nim (binary size: 1.6MiB): https://3code.capocasa.dev/ https://3code.capocasa.dev/
- gip 2mo agoJust tried and although it’s not that polished or fast imo it’s very cool. GLM 5.2 totally free even with a free Vercel account. Make business sense too - fx is the entry point to bring more user to Vercel AI.
- jonstaab 2mo agoI like it from trying it quickly, but is there any way to use it with a provider other than vercel?
- semiinfinitely 2mo agofinally some good sofware
- _pdp_ 2mo agoIt may come across harsh but IMHO the only interesting thing about this project is that it is written in Zig. That's it. Everything else in the harness is largely the same just Vercel-flavoured. The portability benefit is also a bit over-sold imho. I wrote a harness in Go and it is as portable as this ... in fact it deploys straight into Vercel's own sandbox environment on demand without any issues. That being said, did you say GLM 5.2 free? I need to look into that. GLM is remarkably capable model and that alone is worth using the harness in my books.
- _superposition_ 2mo agoThis is exactly how I work today. I've always lived in the terminal but typing bash commands anymore is way too much work and an LLM can produce way better one liners than I can.
- mparramon 2mo agoUX-wise it's quite minimalistic, that seems one of their differentiators. And I'm liking it!
- nullbio 2mo agoThey should spend their efforts making a harness that utilizes tiny AI models on the host in unison with the frontier model, to improve intelligence and capabilities. This is an under-explored area.
- JSR_FDED 2mo agoIn 9 lines of python: (from https://news.ycombinator.com/item?id=49006862 https://news.ycombinator.com/item?id=49006862 ) import json,sys;from subprocess import getoutput as sh;from urllib.request import Request as R,urlopen url=sys.argv[1];h=[];b=dict(model="gpt-5.6",input=h,tools=[dict(type="custom",name="sh")]) while p:=input("> "): h+=[dict(role="user",content=p)];H={"Content-Type":"application/json"} while True: o=(r:=json.load(urlopen(R(url,json.dumps(b).encode(),H))))["output"] h+=o;c=[i for i in o if i["type"]=="custom_tool_call"];z=r["usage"]["total_tokens"]/10500 if not c:print(o[-1]["content"][0]["text"],f'\n[{z:06.3f}%]');break h+=[dict(type="custom_tool_call_output",call_id=i["call_id"],output=sh(i["input"])) for i in c]
- ryuuseijin 2mo agoSince I've seen some other agent tools being suggested, let me throw Maki in the ring as well: https://maki.sh/ https://maki.sh/ - written in rust, super fast startup and rendering - implements token saving techniques - plugins written in lua No affiliation, just think it's a really well made piece of software.
- jatins 2mo agoThis has some nice ideas like indexing (aider like repo map) built in, could be interesting
- pynappo 2mo agobeen enjoying maki too. respects xdg spec (unlike pi), the ui is snappy and pretty much exactly what i want, and i like the choice to keep the lua API similar-ish to neovim.
- Imustaskforhelp 2mo agoLove using maki on 500mb and 1gb ram tiny vps's where opencode sometimes could go OOM. I really love maki, its awesome!
- kzrdude 2mo agoCan it replace pi? Would be good to have a robust and fast replacement.
- nateb2022 2mo agoCan Sprite replace Pepsi?
- mellosouls 2mo agoWould like to try this but the apparent requirement of a credit card (Vercel AI Gateway) and lack of transparency in how to avoid that ever being used is a big fat nope.
- nathan-hello 2mo agoI cloned the repo, ran zig build on 0.16, and the binary was 144MB, after stripping it was 44MB. No where close to 6MB? Am I holding it wrong?
- nateb2022 2mo agoOn macOS (zig 0.16.0) a compile with zig build -Doptimize=ReleaseSmall yields a 5.8M binary for me.
- miki123211 2mo agoI spent 5 minutes on this and still couldn't figure out a way to sign in with my own subscription / direct API key. They're claiming it's possible, but the onboarding is thoroughly broken.
- qznc 2mo agoWhy does everybody use this TUI approach? More minimal to me would be a shell-like prompt. Save yourself the lines above and below. Use readline or something similar.
- vehemenz 2mo agoSign in to Vercel? I don't even know what Vercel is. Sign into Codex, but no Claude Code? However good this software is, it's not going see mainstream adoption.