x402-payable card transaction endpoint on Base, settling in USDC at $0.02 per request.
What it does
This endpoint at lowpaymentfee.com provides a POST-based card transactions API accessible via the x402 payment protocol. It is part of a broader platform offering dozens of pay-per-call endpoints spanning data analytics, AI/ML inference, finance/Web3 data, and infrastructure utilities — all priced at $0.02 per request and settled in USDC on the Base network.
The specific endpoint `/api/v1/cards/19/transactions` is listed under the title "Premium API Access." The x402 challenge confirms it is live, accepting exact-scheme payments of up to 20,000 base units of USDC (0x8335…2913 on Base), which equals $0.02 given USDC's 6 decimals. Payments are sent to address 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3 with a 300-second timeout. No API keys or rate limits are advertised; access is granted purely through the x402 payment header.
Documentation is extremely sparse. The docs, API, pricing, and README pages all render only a "Connect wallet" prompt with no further content. There is no OpenAPI schema, no request/response examples, and no description of what the "cards/19/transactions" resource actually returns or expects as input. The endpoint's purpose — whether it retrieves transaction history for a specific card, creates a transaction, or something else — cannot be determined from the available material. Prospective users should test with caution.
Capabilities
Use cases
- —Querying or creating card transaction records via a single paid POST call
- —Integrating pay-per-call card data into agent workflows without API key management
- —Programmatic access to card transaction data settled on-chain via USDC
Fit
Best for
- —Developers wanting keyless, pay-per-call access to card transaction data
- —AI agents that can settle x402 payments in USDC on Base
- —Projects needing low-cost per-request pricing without subscriptions
Not for
- —Users who need detailed API documentation or OpenAPI schemas before integrating
- —High-volume batch processing where per-request fees add up quickly
- —Anyone requiring non-crypto payment methods
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/cards/19/transactions \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-header>"Endpoint
Quality
The endpoint is live and returns a valid x402 challenge, but there is no documentation, no OpenAPI schema, no request/response examples, and no explanation of what the endpoint actually does. The listing title 'Premium API Access' is generic and uninformative. Effectively a stub.
Warnings
- —No documentation available — docs, API, pricing, and README pages all show only 'Connect wallet'
- —No OpenAPI or request/response schema provided; input and output formats are unknown
- —The purpose of '/api/v1/cards/19/transactions' is unclear — it could be transaction history, creation, or something else
- —The hardcoded card ID '19' in the path suggests this may be a demo or placeholder endpoint
Citations
- —The endpoint returns a valid x402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/cards/19/transactions
- —All endpoints are priced at $0.02 per request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —USDC contract address on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/cards/19/transactions