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You’ll build a paid /weather endpoint with two prices. Any payer can use the standard $0.01 tier. An agent can use the $0.006 tier only if it signs a human proof and its DID holds an ownership attestation.

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Before you start

  • Node.js 20.11.0 or later.
  • An EVM address to receive payments.
  • An x402 facilitator URL that supports Base Sepolia (eip155:84532). The example uses https://x402.org/facilitator. See the x402 facilitator docs for others.
Tested with @billionsnetwork/x402-human-proof-server 0.1.9, @x402/express 2.28 and Node.js 24. Payments are test payments on Base Sepolia. Pairings are checked on production, where the Verified Agent Identity skill records them. See Environments.

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1. Create the project

Create a .env file:

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2. Write and run the server

The server code lives in the Server SDK reference:
  1. Setup makes the server x402-compatible (Step 1), then adds human proof (Step 2). Already running x402? Go straight to Step 2.
  2. Complete Example has both steps in one server.ts, with the command to run it and the 402 response you should see.

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Learn more

x402 Human Proof

How human proof fits into the x402 payment flow, and a live demo.

Server SDK

Usage caps with maxUse, events, storage, rollback hooks, replay protection, testing with an agent, and every option.