at-where

I’ve moved from Twitter to Mastodon and for the last while I’ve found a pretty comfortable home on BlueSky. The interesting part about BlueSky is the open protocol which underpins the network, allowing other services to rapidly layer on my services and content onto the existing social connections. That’s the ATProto layer.

But how, I lamented, are people supposed to discover these other ATProto services?

Luckily for me, all your ATProto data is publicly-available and queryable. So… I can just query each of the people I follow, compile a list of all their ATProto content, and thereby discover other services they use.

at-where does that for anyone: type your handle and it scans the accounts you follow, works out which ATProto apps and services they’ve used (by examining the collections in their public repos), and recommends them ranked by popularity among your follows — with an avatar group of the most active users per service.

Services you already use are excluded by default (with a toggle to show them anyway). There’s no login and no accounts; everything comes from public ATProto data.

For fun, I had Claude Design play with an altitude / atmosphere so Bluesky is the lowest level and then as you scroll you hit rarer and rarer services. It doesn’t quite work because you’re scrolling down whilst going up through the atmosphere but, whatever, it was fun.

How it was built

It’s a Rails 8.1 app leaning on the default stack: SQLite, SolidQueue for the background scanning jobs, SolidCache, and Turbo to stream results in as the scan progresses.