Ask HN: Examples of web apps as composable data

Looking for more examples of a particular style of web app that is close to my heart. For lack of a better name, let's call them "composable data" apps. These applications have (at their core) two functions: (1) collect a piece of data and (2) expose it in a useful way (usually with an API). They tend to focus on atomic data units of a single type (they don't collect just anything). I'll try to offer some examples since I think that my description may be unclear. Last.fm (the old site) atom: a song listened to collection: automatic (scrobbled from media player) expose: web app, API Reading.am https://www.reading.am atom: article that you read collection: manual (post to web app), automatic (hooks to Twitter/FB/etc) expose: web app Pinboard.in https://pinboard.in atom: url collection: manual (post to web app), automatic (hooks to Twitter/FB/etc) expose: web app, api A good litmus test might be how cleanly they map to IFTTT or Zapier workflows. Looking for the Xs and Ys in "Add X to Y." -- Others to consider: - Original Twitter? Maybe Twitter's atom was a status update (or a thought) - Original Delicious? Atom was a URL Early Twitter and Delicious are confusing since they were both data repositories and social networks.