Lightning Labs launches pi402 so AI agents can buy inference with Bitcoin

The open-source Pi extension lets coding agents pay per token over Lightning, with no accounts, API keys, or cards involved

Lightning Labs has released pi402, an open-source extension that lets AI coding agents pay for their own inference in Bitcoin over the Lightning Network.

There is no account signup, no API key, and no credit card. The agent sees a price, pays the invoice, and gets back to work.

The tool was unveiled on November 12, 2026, and is built for the Pi coding agent. It targets a specific and growing problem. Software agents increasingly need to buy compute, but nearly every compute vendor still assumes a human is holding the wallet.

How pi402 actually works

The engine underneath pi402 is L402, a protocol Lightning Labs has been developing for some time. It pairs two pieces of plumbing that were not originally designed to meet.

The first is the HTTP 402 “Payment Required” response. The second is a Lightning invoice, which is a request for a specific amount of Bitcoin payable over the Lightning Network.

When an agent hits a paid endpoint, the server answers with a 402 and an invoice attached. The agent pays it, and the payment settles instantly.

Authentication runs through macaroons, a type of credential token. The result is pay-per-token billing. Instead of a monthly plan or a prepaid credit balance, the agent pays for exactly the tokens it consumes, request by request.