Simon Willison’s Weblog

Bluesky WebSocket Firehose. Very quick (10 seconds of Claude hacking) prototype of a web page that attaches to the public Bluesky WebSocket firehose and displays the results directly in your browser.

Here's the code - there's very little to it, it's basically opening a connection to wss://jetstream2.us-east.bsky.network/subscribe?wantedCollections=app.bsky.feed.post and logging out the results to a <textarea readonly> element.

Bluesky's Jetstream isn't their main atproto firehose - that's a more complicated protocol involving CBOR data and CAR files. Jetstream is a new Go proxy (source code here) that provides a subset of that firehose over WebSocket.

Jetstream was built by Bluesky developer Jaz, initially as a side-project, in response to the surge of traffic they received back in September when Brazil banned Twitter. See Jetstream: Shrinking the AT Proto Firehose by >99% for their description of the project when it first launched.

The API scene growing around Bluesky is really exciting right now. Twitter's API is so expensive it may as well not exist, and Mastodon's community have pushed back against many potential uses of the Mastodon API as incompatible with that community's value system.

Hacking on Bluesky feels reminiscent of the massive diversity of innovation we saw around Twitter back in the late 2000s and early 2010s.

Here's a much more fun Bluesky demo by Theo Sanderson: firehose3d.theo.io (source code here) which displays the firehose from that same WebSocket endpoint in the style of a Windows XP screensaver.