We're building the codex we wish we had.
Billie Brain started with a simple frustration: every "AI assistant" forgets you the moment you close the tab. Real engineering work isn't a one-shot prompt — it's a long conversation with code, decisions, tradeoffs and people. So we built the substrate for that.
A persistent codex. Sandboxed execution. Scoped connectors to the tools you already trust. No magic, no theater — just an honest second brain that ships.
Memory is the product
Stateless chat is a toy. The codex remembers your decisions and grows with the work.
Tools beat tricks
Real connectors, real sandboxes, real diffs, and clear progress states.
Honest by default
We say what we don't know. We log what we do. We never train on your data.
Where we're going.
Right now Billie Brain is in private beta with a small group of senior engineers and engineering teams. We're working toward an open codex format, self-hosted runtimes, and a permission model that treats your code with the seriousness it deserves.
If that resonates — join us. Or just kick the tires.