L402

What L402 enables

L402 connects API access with a payment through the Bitcoin Lightning network. The service supplies an invoice and an access credential; after payment, the client adds proof of payment. Individual API calls or other digital services can be paid for as they are requested.

Connections with other protocols

• Like x402 and MPP, L402 addresses paid access to a resource. L402 uses Lightning invoices and cryptographic access credentials.
• Aperture from the Lightning Labs ecosystem can act as a proxy handling payment and access verification for a service.

Versions and licence

Published version

No separate version stated

Working draft

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The JavaScript packages @lightninglabs/l402 and @lightninglabs/l402-ai are published as 0.1.0. The SDK repository contains a Rust core and Go and Python bindings; package versions are not a global protocol version.

Licence / terms

L402sdk: MIT OR Apache-2.0. Terms for the specification and other implementations are in their respective repositories.
Licence and terms ↗

An example flow

1. A client requests a paid API. The server returns HTTP 402, a Lightning invoice and a macaroon as an access credential.
2. The client pays the invoice through Lightning and receives proof of payment, called the preimage.
3. It repeats the request with the macaroon and preimage in the Authorization header.
4. The server checks both and delivers the requested resource.

SDKs and examples

These libraries and examples help you get started. Each entry lists the language, package and supported version.

Practical integration

• A macaroon can restrict access to particular services or a narrower scope of use.
• The SDKs listed here are from Lightning Labs. The PyPI name l402 refers to a separate library published by Fewsats.

Related protocols

Original sources

• Specification ↗
• SDK ↗
• Aperture ↗
• JavaScript package 0.1.0 ↗
• AI package 0.1.0 ↗
• Go bindings ↗
• PyPI l402: separate Fewsats project ↗