x402-gated card transaction endpoint on Base, pay $0.02 per request in USDC.
What it does
This endpoint at lowpaymentfee.com provides access to a card transactions resource via the x402 payment protocol. The specific path `/api/v1/cards/5/transactions` accepts POST requests and is gated behind a per-call USDC payment on the Base network. The x402 challenge indicates a maximum cost of 20,000 base units of USDC (0.02 USD) per request, settled to a specified wallet address.
The broader lowpaymentfee.com platform advertises a suite of pay-per-call APIs spanning data analytics, AI/ML inference (sentiment analysis, summarization, classification, embeddings), finance/Web3 data (price feeds, exchange rates, token quotes, gas estimates), and infrastructure utilities (geocoding, validation, conversion, generation). All endpoints are listed at $0.02 per request with no API keys, no rate limits, and no minimum commitments. However, the specific `/api/v1/cards/5/transactions` endpoint is not listed on the homepage among the advertised APIs, and no documentation describes its request or response schema.
Because the crawled docs pages (`/docs`, `/api`, `/pricing`, `/README`) all returned only a "Connect wallet" prompt with no substantive content, the actual functionality, expected request body, and response format for this endpoint remain unknown. Users should treat this as a minimally documented endpoint and test carefully before relying on it in production.
Capabilities
Use cases
- —Submitting or querying card transaction data via a pay-per-call model
- —Integrating x402-compatible agents with financial transaction endpoints
- —Testing x402 protocol payment flows on Base network
Fit
Best for
- —Developers experimenting with x402 payment protocol integrations
- —Agents that need to make per-call payments in USDC on Base
- —Low-volume, on-demand access to card transaction data without API key management
Not for
- —Production workloads requiring well-documented request/response schemas
- —High-volume use cases where per-call pricing may be inefficient
- —Users who need detailed API documentation before integration
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/cards/5/transactions \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>" \
-d '{}'Endpoint
Quality
The endpoint is live (returns a valid x402 402 challenge), but there is no documentation, no OpenAPI schema, no request/response examples, and the specific cards/5/transactions path is not listed among the provider's advertised APIs. All doc pages returned only 'Connect wallet' with no content.
Warnings
- —The /api/v1/cards/5/transactions endpoint is not listed among the provider's advertised APIs on the homepage — its purpose is unclear.
- —All documentation pages (/docs, /api, /pricing, /README) returned no substantive content, only a 'Connect wallet' prompt.
- —No request body schema or response schema is available; the endpoint's actual functionality is unknown.
- —The endpoint references 'cards/5' which may be a specific resource ID rather than a general-purpose API path.
Citations
- —The x402 challenge specifies maxAmountRequired of 20000 base units of USDC (USD Coin, 6 decimals = $0.02) on Base network.https://lowpaymentfee.com/api/v1/cards/5/transactions
- —The platform advertises $0.02 per request with no API keys, no rate limits, and instant access on Base network.https://lowpaymentfee.com
- —The homepage lists APIs across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categories but does not include /api/v1/cards/5/transactions.https://lowpaymentfee.com
- —Documentation pages (/docs, /api, /pricing, /README) returned only 'Connect wallet' with no substantive content.https://lowpaymentfee.com/docs