October 2, 2025
You might have heard about the AT protocol (if not, read this!)
Together, all servers speaking the AT protocol comprise the atmosphere—a web of hyperlinked JSON. Each piece of JSON on the atmosphere has its own at:// URI:
But where do they point, exactly?
Given an at:// URI, how do you locate the corresponding JSON?
In this post, I’ll show you the exact process of resolving an at:// URI step by step. Turns out, this is also a great way to learn the details of how at:// works.
Let’s start with the structure of a URI itself.
As you might know, a URI often contains a scheme (for example, https:// ), an authority (like wikipedia.com ), a path (like /Main_Page ), and maybe a query.
In most protocols, including https:// , the authority part points at whoever’s hosting the data. Whoever created this data is either not present, or is in the path:
https:// /profile/ /post/3lzy2ji4nms2z bsky.app ruuuuu.de the app the user
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