Hummingbird

Hummingbird handled the low-level work between an app and the Bitcoin network. It connected directly to a node, replayed the chain from a given block, watched the mempool for new transactions, and passed each relevant one to the app’s own state machines, so a Bitcoin app could react to transactions as they happened.

I built it alongside Bit.sv and released it as open source. In late 2020 I rewrote it as Hummingbird 2 to rebuild PoW.Market on cheaper, managed data services; the Building on Bitcoin #2 video walks through that rebuild.