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PayloadPierPurchasing APIs
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Pay for one comparison with x402

Base mainnet wallet purchasing is enabled at 0.25 USDC per comparison. The mainnet payment challenge has been verified; the first genuine mainnet payment remains unverified. Test USDC has no cash value. Live card subscriptions and prepaid API-key usage remain separate.

Current payment network

Chain: Base mainnet (eip155:8453). USDC contract: 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913. Price: 250000 token base units, or 0.25 USDC. The challenge returned by the endpoint is authoritative; refuse a changed chain, asset, price or unexpected receiver. Use Base USDC, not Ethereum-mainnet or testnet USDC.

The payment flow

  1. POST the normal comparison JSON to https://payloadpier.com/api/x402/compare. Supply a unique 16–100 character Idempotency-Key. JSON only; 5 MiB and 5,000 rows per snapshot limits apply.
  2. An unpaid valid request returns HTTP 402 with a version-2 PAYMENT-REQUIRED challenge. Inspect its network, USDC contract, amount and receiver before signing. The launch price is 0.25 USDC per successful comparison.
  3. A compatible x402 client signs a payment authorization with its own funded buyer wallet. Send the resulting PAYMENT-SIGNATURE header with exactly the same JSON and operation key. No PayloadPier login or prepaid API key is required for this endpoint.
  4. The server verifies the authorization and settles through the CDP facilitator. A confirmed payment returns the comparison, billing transaction reference and PAYMENT-RESPONSE header. Save these and your result immediately.

A receiving wallet address alone cannot sign a buyer payment. Give each agent its own spending controls and keep signing keys in its secret store. PayloadPier never needs your wallet seed phrase or private key.

The wallet endpoint allows 60 attempts per source IP per fixed UTC minute, including challenge and payment requests. HTTP 429 includes Retry-After; retain the same operation key. Shared networks share this limit.

Retries and uncertain outcomes

Reusing a recorded operation returns HTTP 409 without another settlement. The original result is not retained for replay. If a request times out or settlement is uncertain, preserve the operation key and payment references; contact support before paying again with a new key. Invalid input is rejected before requesting payment. A 402 challenge is not evidence that funds moved.

Verified test

On October 14, 2026, an isolated buyer paid 0.25 Base Sepolia test USDC, received the expected 20% unit-cost increase result, and received 409 on replay. The successful onchain receipt matched the saved settled payment record. This was a test, not customer revenue. Mainnet is now configured; the first genuine mainnet customer purchase and reconciliation remain.

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