x402: Expired offer

A deliberately broken x402 endpoint charging 0.0001 USDC on Base Sepolia, advertising x402.org.

Pick a protocol

x402 uses its own PAYMENT-REQUIRED header. MPP uses the standard HTTP auth framework, with no facilitator.

x402Coinbase. PAYMENT-REQUIRED and PAYMENT-SIGNATURE headers.MPPTempo and Stripe. WWW-Authenticate: Payment, no facilitator.

New to these? Read what x402 and MPP put on the wire.

Pick a network

Testnets only. Nothing here can move real money.

Network

Asset

USDC, 6 decimals

Set the price

Amounts are atomic units of the asset, so no decimal point.

Amount

= 0.0001 USDC

Scheme

Recipient

Defaults to this network's burn address.

Pick a facilitator

What the challenge advertises for verify and settle. test402 issues challenges; it never settles.

Facilitator

Public testnet facilitator from the x402 docs.

Sign offers and receipts

The offer-receipt extension: a signed commitment to the terms on the 402, and a signed statement of delivery on the 200.

Signed artifacts

Offers and receipts as JWS compact strings, signed ES256K. The payload lives inside the signature, and the key is named by kid — resolved from /.well-known/did.json on this host.

Choose a behavior

Compliant by default. Every deviation is named, and never on by accident.

Behavior

The offer's validUntil is already in the past, though the signature is genuine. A correct client checks the expiry before paying rather than trusting a valid signature alone.

Your endpointExpired offer

/api/x402?offerReceipt=jws&quirk=expired-offer

Try it

curl -i "https://test402.com/api/x402?offerReceipt=jws&quirk=expired-offer"

Returns 402 whose signed offer has a validUntil in 2020. Spec §4.6: a client should check expiration before paying, and the server may reject a payment against an expired offer.

The signature is minted per request and shown here as a placeholder, and the offer’s validUntil is always 300s past the moment you ask. Run the curl to see the real artifact.

Response it will return (HTTP 402)

PAYMENT-REQUIRED: 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

{
  "x402Version": 2,
  "error": "PAYMENT-SIGNATURE header is required",
  "resource": {
    "url": "https://test402.com/api/x402?offerReceipt=jws&quirk=expired-offer",
    "description": "test402 challenge",
    "mimeType": "application/json"
  },
  "accepts": [
    {
      "scheme": "exact",
      "network": "eip155:84532",
      "amount": "100",
      "asset": "0x036CbD53842c5426634e7929541eC2318f3dCF7e",
      "payTo": "0x0000000000000000000000000000000000000402",
      "maxTimeoutSeconds": 300,
      "extra": {
        "name": "USDC",
        "version": "2",
        "assetTransferMethod": "eip3009"
      }
    }
  ],
  "extensions": {
    "https://test402.com/extensions/facilitator": {
      "id": "x402org",
      "url": "https://x402.org/facilitator"
    },
    "offer-receipt": {
      "info": {
        "offers": [
          {
            "format": "jws",
            "acceptIndex": 0,
            "signature": "<signed per request -- run the curl to see it>"
          }
        ]
      },
      "schema": {
        "$schema": "https://json-schema.org/draft/2020-12/schema",
        "type": "object",
        "properties": {
          "offers": {
            "type": "array",
            "items": {
              "type": "object",
              "properties": {
                "format": {
                  "type": "string",
                  "const": "jws"
                },
                "acceptIndex": {
                  "type": "integer"
                },
                "signature": {
                  "type": "string",
                  "description": "JWS compact serialization containing the offer payload"
                }
              },
              "required": [
                "format",
                "signature"
              ]
            }
          }
        },
        "required": [
          "offers"
        ]
      }
    }
  },
  "note": "test402 scenario. quirk=expired-offer"
}