x402

x402 is an open standard for internet native payments. It aims to support all networks (both crypto & fiat) and forms of value (stablecoins, tokens, fiat).

app.use(
  paymentMiddleware(
    {
      "GET /weather": {
        accepts: [...],                 // As many networks / schemes as you want to support
        description: "Weather data",    // what your endpoint does
      },
    },
  ),
);
// That's it! See examples/ for full details

# All available reference sdks
npm install @x402/core @x402/evm @x402/svm @x402/axios @x402/fetch @x402/express @x402/hono @x402/next @x402/paywall @x402/extensions

# Minimal Fetch client
npm install @x402/core @x402/evm @x402/svm @x402/fetch

# Minimal express Server
npm install @x402/core @x402/evm @x402/svm @x402/express

pip install x402

go get github.com/x402-foundation/x402/go

Principles

• Open standard: x402 is an open standard, freely accessible and usable by anyone. It will never force reliance on a single party.
• HTTP / Transport Native: x402 is meant to seamlessly complement existing data transportation. It should whenever possible not mandate additional requests outside the scope of a typical client / server flow.
• Network, token, and currency agnostic: we welcome contributions that add support for new networks (both crypto and fiat), signing standards, or schemes, so long as they meet our acceptance criteria laid out in CONTRIBUTING.md. x402 may extend support to fiat based networks, but will never deprioritize onchain payments in favor of fiat payments.
• Backwards Compatible: x402 will not deprecate support for any existing networks unless such removal is deemed necessary for the security of the standard. Whenever possible, x402 will aim for backwards compatibility for non-major version changes.
• Trust minimizing: all payment schemes must not allow for the facilitator or resource server to move funds, other than in accordance with client intentions
• Easy to use: It is the goal of the x402 community to improve ease of use relative to other forms of payment on the Internet. This means abstracting as many details of crypto as possible away from the client and resource server, and into the facilitator. This means the client/server should not need to think about gas, rpc, etc.

Ecosystem

The x402 ecosystem is growing! Check out our ecosystem page to see projects building with x402, including:

• Client-side integrations
• Services and endpoints
• Ecosystem infrastructure and tooling
• Learning and community resources

Want to add your project to the ecosystem? See our demo site README for detailed instructions on how to submit your project.

Roadmap: see ROADMAP.md

Documentation: see docs/ for the GitBook documentation source

Terms:

• resource: Something on the internet. This could be a webpage, file server, RPC service, API, any resource on the internet that accepts HTTP / HTTPS requests.
• client: An entity wanting to pay for a resource.
• facilitator: A server that facilitates verification and execution of payments for one or many networks.
• resource server: An HTTP server that provides an API or other resource for a client.

Technical Goals:

• Permissionless and secure for clients, servers, and facilitators
• Minimal friction to adopt for both client and resource servers
• Minimal integration for the resource server and client (1 line for the server, 1 function for the client)
• Ability to trade off speed of response for guarantee of payment
• Extensible to different payment

... View full README on GitHub