x402-gated card-transaction endpoint on Base, paying per request in USDC.
What it does
This endpoint at lowpaymentfee.com exposes a card-transactions resource at `/api/v1/cards/7/transactions` behind an x402 paywall. The x402 challenge indicates the endpoint accepts POST requests and settles payments on the Base network using USDC (contract 0x8335…2913) with the "exact" payment scheme. The maximum amount required per call is 20,000 base units of USDC, which at 6 decimals equals $0.02 per request.
The broader lowpaymentfee.com platform advertises a suite of pay-per-request APIs spanning data analytics, AI/ML inference (sentiment analysis, summarization, classification, embeddings), finance/Web3 (price feeds, exchange rates, token quotes, gas estimates), and infrastructure utilities (geocoding, validation, conversion, generation) — all priced at $0.02 per request with no API keys, no rate limits, and no commitments. However, the specific endpoint listed here (`/api/v1/cards/7/transactions`) is not explicitly documented on the site's landing page among those categories, and its exact functionality is unclear. The name suggests it returns or creates transactions associated with a card resource (card ID 7), but no schema, field definitions, or example payloads are available.
The endpoint is confirmed live: the probe received a proper HTTP 402 with a valid x402 v1 challenge. Documentation pages (/docs, /pricing, /api, /README) all returned only a "Connect wallet" prompt with no substantive content, so detailed request/response schemas are unknown.
Capabilities
Use cases
- —Retrieving or creating transactions associated with a card resource via a single paid POST call
- —Integrating pay-per-use card transaction data into agent workflows without API key management
- —Programmatic access to card transaction records settled via on-chain USDC micropayments
Fit
Best for
- —Agents or services that need card-transaction data with zero-setup authentication
- —Developers wanting to test x402 payment flows on Base with low per-call costs
- —Workflows requiring on-demand, keyless API access paid in USDC
Not for
- —Users needing detailed API documentation or guaranteed SLA before integrating
- —High-volume batch processing where $0.02/request adds up significantly
- —Anyone without a Base-compatible USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/cards/7/transactions \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live (valid 402 challenge captured), but there is no documentation, no request/response schema, and the specific endpoint (/api/v1/cards/7/transactions) is not listed among the site's advertised APIs. The docs, pricing, and README pages are all empty stubs. Functionality must be entirely inferred from the URL path.
Warnings
- —The endpoint /api/v1/cards/7/transactions is not listed among the provider's advertised APIs — its purpose is unclear.
- —All documentation pages (/docs, /pricing, /api, /README) returned no content beyond a 'Connect wallet' prompt.
- —No request or response schema is available; input format and output fields are unknown.
- —The hardcoded card ID '7' in the path suggests this may be a demo or placeholder resource.
Citations
- —The x402 challenge requires 20,000 base units of USDC on Base network per request (= $0.02).https://lowpaymentfee.com/api/v1/cards/7/transactions
- —The platform advertises $0.02/request pricing with no API keys, no rate limits, and instant access.https://lowpaymentfee.com
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913.https://lowpaymentfee.com/api/v1/cards/7/transactions