Lightning Labs, the company behind Lightning Network developer tools, announced a dedicated website for L402 on Wednesday, positioning the protocol as a rail for AI agents to pay in bitcoin.
"With L402, agents can pay with bitcoin and natively authenticate. No accounts, no intermediaries, no humans involved," the company said in the post, describing L402 as "the protocol for machine-to-machine commerce on Lightning."
What is new is the site, not the protocol. L402, the Lightning HTTP 402 protocol, already exists in Lightning Labs' stack. Aperture, an implementation of the standard, "is used today by Lightning Loop, a non-custodial swap service for Bitcoin and Lightning," according to the company's documentation.
L402 is "the standard for selling and buying digital resources" that "allows services to charge for API endpoints in a way that is easy for AI agents to participate," the documentation states.
The mechanism reuses HTTP's 402 status code. When a client requests a gated endpoint, "the server responds with HTTP 402 Payment Required and a WWW-Authenticate header containing a token and a Lightning invoice," and the token contains the invoice's payment hash, the documentation says.
