x402-gated card transaction endpoint on Base, pay-per-call with USDC.
What it does
This endpoint at lowpaymentfee.com exposes a card transactions resource at `/api/v1/cards/72/transactions` behind an x402 payment challenge. It accepts POST requests and is settled on the Base network using USDC (contract 0x8335…2913). The maximum amount required per call is 20,000 base units of USDC, which at 6 decimals equals $0.02 per request.
The hosting site lowpaymentfee.com advertises a broad catalog of pay-per-request APIs spanning data & analytics, AI/ML inference, finance/Web3, and infrastructure utilities — all priced at $0.02 per request with no API keys, no rate limits, and no commitments. However, the specific endpoint being listed here (`/cards/72/transactions`) is not explicitly documented on the site's landing page among the advertised APIs. Its exact functionality — whether it returns transaction history for a specific card, creates a new transaction, or something else — is not documented in any crawled material.
The x402 challenge is live and well-formed (HTTP 402 returned with a valid accepts array). No OpenAPI schema, detailed docs, or example request/response payloads were found. The docs, API, pricing, and README pages all returned only a "Connect wallet" prompt with no substantive content. Because the endpoint's actual behavior is undocumented, agents should treat this as an exploratory integration.
Capabilities
Use cases
- —Querying or creating card transaction records via a pay-per-call model
- —Integrating card transaction data into agent workflows without API key management
- —Programmatic access to card-level transaction information settled in USDC on Base
Fit
Best for
- —Agents that can settle x402 payments in USDC on Base
- —Use cases needing keyless, per-request API access to card transaction data
- —Developers exploring x402 protocol integrations
Not for
- —Users who need detailed API documentation or guaranteed SLAs before integrating
- —High-volume batch processing where per-request pricing at $0.02 adds up quickly
- —Anyone needing non-USDC or non-Base settlement options
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/cards/72/transactions \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The x402 challenge is live and well-formed, confirming the endpoint exists and accepts USDC on Base at $0.02/request. However, there is no documentation for this specific endpoint's purpose, no request/response schema, and no examples. The crawled docs pages are empty. The endpoint path suggests card transactions but its actual behavior is unknown.
Warnings
- —Endpoint /api/v1/cards/72/transactions is not listed among the site's advertised APIs — its purpose and expected request/response format are undocumented.
- —All documentation pages (docs, API, pricing, README) returned only a 'Connect wallet' prompt with no substantive content.
- —No OpenAPI spec, request schema, or response schema available — callers must discover behavior experimentally.
- —The broader site advertises many API categories but none of the crawled pages provide technical details.
Citations
- —The x402 challenge returns HTTP 402 with maxAmountRequired of 20000 base units of USDC on Base network.https://lowpaymentfee.com/api/v1/cards/72/transactions
- —USDC asset contract is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base.https://lowpaymentfee.com/api/v1/cards/72/transactions
- —Site advertises $0.02/request pricing with no API keys, no rate limits, and instant access on Base network.https://lowpaymentfee.com