The Importance of Backfillability

Last week, we released Tap , a new synchronization tool for AT Protocol. It's a fantastic utility and fulfills a real developer need, especially for Atmosphere infrastructure providers.

There's also something philosophically important: AT Protocol is designed so that anyone with sufficient resources can backfill the entire network. No special partnerships or paid API tiers required, just provision the storage and bandwidth and do it.

Right now, you can point Tap at a relay and, over the course of days or weeks, download every public post, every follow relationship, every profile. It's terabytes of data. It takes real infrastructure. Not every developer, in fact the vast majority, will never need to do this. But it's technically possible, and critically, it doesn't require our permission.

Compare this to how centralized platforms work. If you want historical data — to study how a news story evolved over months, or analyze community formation patterns — you enter into enterprise partnerships with specific pricing and terms, assuming you can even get access at all . The platform becomes the only entity that could answer questions requiring that kind of longitudinal view.

This creates a specific power dynamic. When a platform controls the only copy of the comprehensive dataset, access becomes a negotiation. Researchers who produce findings the platform doesn't like might find their access restricted . Journalists investigating platform decisions hit walls. Smaller developers can't afford the partnership tiers that give them the data they need to build useful tools.

AT Protocol inverts this. Every PDS on the network can be aggregated by Relays. The Firehose is an event stream of activity across those Relays, potentially all the activity on the network. Bluesky-the-company operates infrastructure but can't gatekeep the data because the architecture doesn't allow it.

The practical result: if you want to study information flow across the network, analyze how communities self-organize, or do sentiment analysis across millions of people's posts, you can get the data yourself. No approval necessary.

And if you want to build your own network completely separate from Bluesky's, Tap brings you one step closer.

Platforms often start open and gradually close down — first restricting certain endpoints, then repricing access, then limiting who even qualifies for partnerships. These small steps eventually lead to an enclosed digital commons.

Backfillability as a core principle means the Atmosphere is a network where innovation doesn't require permission. When researchers can work independently, developers can just make things without needing approval, communities can run their own infrastructure, the network becomes more resilient and useful.