true402
for agents & customers

Buy with
one header.

No account. No API key. Your wallet is the identity. An agent discovers a service, gets a price as HTTP 402, signs USDC, and retries with a single X-PAYMENT header. Receiving is keyless; the facilitator does the on-chain work.

§01 · discover

List what’s for sale — free.

Browsing models, services, and feeds never costs anything. Only the call itself is gated.

bash 
curl -s https://true402.dev/api/v1/models | jq '.data[0]'
§02 · the 402

Ask, and get a price.

A gated endpoint answers 402 Payment Required with everything needed to pay: amount, the USDC asset, where to pay, and which facilitator settles it.

402 response 
curl -i -X POST https://true402.dev/api/v1/chat/completions \
  -H 'content-type: application/json' \
  -d '{"model":"gpt-4o-mini","messages":[{"role":"user","content":"hi"}]}'

HTTP/1.1 402 Payment Required
{
  "x402Version": 2,
  "accepts": [{
    "scheme": "exact",
    "network": "eip155:8453",
    "maxAmountRequired": "495",            // atomic USDC (6dp) -> $0.000495
    "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "payTo": "0xFe25…A9C4",
    "facilitatorUrl": "https://open.x402.host"
  }]
}
§03 · pay & retry

Sign once, resend.

Your agent signs a USDC EIP-3009 authorization that matches the 402, base64-encodes it, and resends as X-PAYMENT. x402 client libraries automate this sign-and-retry, but the wire format is simple:

decoded X-PAYMENT 
# X-PAYMENT is base64 of this — your agent signs the USDC authorization off-chain.
# No gas, no on-chain call by you: the facilitator submits it.
{
  "x402Version": 2,
  "scheme": "exact",
  "network": "eip155:8453",
  "payload": {
    "signature": "0x…",
    "authorization": {
      "from": "0xYourWallet",
      "to":   "0xFe25…A9C4",     // payTo from the 402
      "value": "495",            // maxAmountRequired from the 402
      "validAfter": "…", "validBefore": "…", "nonce": "0x…"
    }
  }
}
§04 · settled

200, and you’re in.

The facilitator verifies the signature; the service responds. Settlement is asynchronous, so the response doesn’t wait on the chain.

200 OK 
curl -X POST https://true402.dev/api/v1/chat/completions \
  -H 'content-type: application/json' \
  -H "X-PAYMENT: <base64 payload>" \
  -d '{"model":"gpt-4o-mini","messages":[{"role":"user","content":"hi"}]}'

HTTP/1.1 200 OK
{ "id": "chatcmpl-x7", "choices": [{ "message": { "content": "…" } }] }
§05 · point your agent

Machine discovery.

Agents find true402 without reading this page:

Then browse the catalog to see what’s live.