x402 List is the open directory of all services implementing the x402 payment protocol. It provides continuous monitoring, uptime statistics, and pricing data for every listed API.

Can I embed an x402-list badge on my site?

Yes. Any listed service can embed the x402-list badge as an SVG on its website or README. It is served from /badge/ .svg and shows the live listing state. Add ?data=uptime for the uptime we measure (window ?period=24h|7d|30d|90d, default 30d), and ?theme=light for a light surface.

About the x402 Protocol and x402 List

What is the x402 Protocol?

x402 is an open payment protocol built on HTTP 402 Payment Required. It enables machine-to-machine API payments using cryptocurrency. When an AI agent requests an x402-enabled endpoint, the server responds with a 402 status code and payment details. The agent's payment facilitator completes the crypto transaction automatically, and the server verifies payment then delivers the response. No API keys, subscriptions, or manual signup required. Any agent that can pay can access any x402 service instantly. The protocol is documented at x402.org.

What is x402 List?

x402 List is an agent-first directory of services implementing the x402 payment protocol. It is designed primarily for consumption by AI agents and automated systems via a structured JSON API, and remains fully browsable by humans. Every service entry, uptime metric, and price point that appears on these pages is also available as machine-readable JSON at /api/v1/*, described by an OpenAPI 3.1 specification, and summarized for LLMs at /llms.txt and /llms-full.txt. Services are checked continuously and ranked by reliability, response time, and cost. How each of those numbers is measured (what earns the verified checkmark, how uptime is computed, how on-chain facilitator volume is counted) is documented on the methodology page.

How x402 Works

1. Agent sends an HTTP request to an x402-enabled endpoint.
2. Server responds with HTTP 402 and an accepts[] payload describing accepted payment methods, amounts, and network details.
3. The agent's payment facilitator reads the payload and completes the crypto payment on the specified network.
4. Server verifies the on-chain payment and returns the requested data in the response body.

The entire flow is automatic. Agents handle payment without human intervention. Servers enforce payment at the HTTP layer, before any business logic executes.

How to Submit a Service

If you run an API that implements the x402 protocol, you can list it in the directory for free. Submit your service at /submit with your service name, base URL, website, email, category, description, and endpoint paths. Supported networks and pricing are detected automatically from your 402 responses, so you do not provide them. On submission we automatically probe your endpoints to confirm they return a valid 402 response with a well-formed accepts[] payload, then manually review the results. Once approved, your service appears in the directory and monitoring begins.

Already listed? You can update your listing's metadata (name, description, website, category, new endpoints) yourself from /services/<slug>/update: ownership is proven with a one-time domain proof published under your service's /.well-known/ path, and every change is reviewed manually before going live. Measured data such as uptime, pricing, and the verified flag stays read-only for everyone.

The x402-list Badge

Listed services can embed the x402-list badge, a continuously-monitored trust marker, on their own website or README. The badge and the live widget now share a single embed page: x402-list.com/widget#badge.

API Access

The full x402 List directory is available as structured JSON at /api. The API returns every listed service with current uptime, pricing, response times, and endpoint details. It is designed for programmatic consumption by AI agents, aggregators, and developer tools. No authentication required. Responses include pagination and filtering parameters for large result sets. Reads are free for agents and point queries; sustained bulk pulling beyond 2,000 requests per day per IP is metered via x402 at $0.01 per request. A first-party MCP server exposes the same data to Model Context Protocol clients, hosted at mcp.x402-list.com/mcp or local via npx -y x402-list-mcp.

How do AI agents use x402 for payments?

AI agents send an HTTP request to an x402 endpoint. The server responds with HTTP 402 and payment details. The agent's payment facilitator completes the crypto transaction, and the server delivers the response. No API keys or subscriptions required.