PayAPI Market

By · Published 2026-09-13 · Last updated September 13, 2026 · 3 min read

x402 is the payment protocol. PayAPI is the marketplace.

x402 is not a shop. It is a payment standard.

When an AI agent calls a paid API, the server can answer HTTP 402 Payment Required. The agent pays in USDC (on Base, in our case) and retries. No API key. No monthly plan for that call. That protocol is x402. Coinbase and the x402 docs own that story. We do not pretend otherwise.

PayAPI Market is the shop that sits on top of it.

You list an API. Agents discover it (web, or free MCP at https://payapi.market/mcp). When they need a fact you own, they pay per call. The money goes to you. Providers keep 100%. Listing is free.

That is the difference:

  • x402 = how the payment happens
  • PayAPI Market = where agents find APIs and providers earn

Live catalogue

As of 12 Sep 2026 (from https://payapi.market/llms.txt):

  • 150 live APIs
  • 1,045 endpoints
  • 82 providers
  • 133 settlement-verified (we paid the route from our wallet and got real product back, on-chain on Base)

Any industry that can expose an API. On the same rails you will find companion-plant data (PlantPair) and FDA 510(k) medical-device clearances. Same model. Pay per call.

Who this is for

If you already sell to humans (keys, dashboards, invoices), keep doing that. PayAPI is an extra till for agent buyers. Same product. New channel.

If you are building an agent, you do not collect 50 API keys. You search the marketplace, pay USDC, get the response.

How an agent pays

  1. Agent hits the endpoint.
  2. Server returns 402 with the price and wallet.
  3. Agent pays USDC on Base.
  4. You get the money. You keep 100%.

FAQ

What is x402? A payment protocol that uses HTTP 402 so a client (often an agent) can pay for a request in USDC, without an API key.

What is an x402 marketplace? A catalogue of APIs that accept that payment. PayAPI Market is one. Browse at https://payapi.market/marketplace

Is listing free? Yes. Providers keep 100% of what the call earns.

Do I need to replace RapidAPI? No. RapidAPI is built for human developers with keys and plans. PayAPI is built for agents that pay per request. Full comparison: https://payapi.market/blog/payapi-market-vs-rapidapi

How do I list? https://payapi.market/list

Next

List free: https://payapi.market/list

Browse: https://payapi.market/marketplace

Agents / MCP: https://payapi.market/agents

Chet Parker

PayAPI Market

https://payapi.market