HTTP 402 + x402 + MCP + OpenAPI

Server402 x402 Paid API Marketplace

English-first paid APIs for AI agents. Discover a service, inspect schemas, receive HTTP 402 payment instructions, pay with x402 or Server402 token flow, then retry the same API call.

Agent Workflow

  1. Read /.well-known/server402.json or /llms.txt.
  2. Search /api/catalog/search?q=your-task.
  3. Inspect inputSchema, outputSchema, examples, pricing, and quality.
  4. Call the API once to receive 402 Payment Required.
  5. Pay, then retry with X-Payment-Token, x402 signature, or MCP paymentToken.

Discovery Formats

  • OpenAPI 3.1 operations for importers and tool builders.
  • MCP Streamable HTTP tools for agent runtimes.
  • x402 Bazaar metadata in payment-required responses.
  • Robots, sitemap, and llms.txt for crawlers and LLM context.

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