Pay-per-call card transaction API on Base network via x402, settled in USDC at $0.02/request.
What it does
This endpoint at lowpaymentfee.com provides access to a card transactions resource (`/api/v1/cards/50/transactions`) via the x402 payment protocol. It accepts POST requests and charges $0.02 per call (20,000 base units of USDC on Base network, where USDC uses 6 decimals). Payment is settled on-chain to a specified wallet address using the "exact" scheme.
The provider operates a broader platform offering multiple API categories including Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructure utilities — all priced uniformly at $0.02 per request. The platform advertises no API keys, no rate limits, and instant access. However, documentation for this specific endpoint is extremely sparse: the crawled docs, API, pricing, and README pages all returned only a "Connect wallet" prompt with no further technical detail.
The specific functionality of the `/api/v1/cards/50/transactions` endpoint is unclear from available materials. The path suggests it retrieves or creates transactions associated with card ID 50, but no request/response schema, field definitions, or usage examples are documented. The endpoint is confirmed live (returns a valid 402 challenge), but users should expect to experiment or contact the provider for integration details.
Capabilities
Use cases
- —Retrieving or creating transactions for a specific card via programmatic access
- —Integrating card transaction data into automated agent workflows
- —Demonstrating x402 protocol payment flows on Base network
Fit
Best for
- —Developers experimenting with x402 payment protocol
- —Agents needing pay-per-call card transaction access without API keys
- —Projects already operating on Base network with USDC
Not for
- —Production use cases requiring documented request/response schemas
- —High-volume batch processing where per-call pricing is inefficient
- —Users who need detailed API documentation before integrating
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/cards/50/transactions \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402_payment_token>"Endpoint
Quality
The endpoint is live and returns a valid x402 challenge, but there is no documentation of request parameters, response schema, or what 'cards/50/transactions' actually returns. The crawled pages beyond the landing page are all empty wallet-connect prompts. This is effectively a stub listing.
Warnings
- —No request or response schema documented anywhere
- —The specific purpose of /api/v1/cards/50/transactions is unclear — path suggests card-specific data but no details available
- —All documentation pages (docs, api, pricing, README) returned only 'Connect wallet' with no content
- —The card ID '50' is hardcoded in the path — unclear if this is a demo or a real resource
Citations
- —Endpoint returns 402 with x402 challenge requiring USDC payment on Base networkhttps://lowpaymentfee.com/api/v1/cards/50/transactions
- —Platform charges $0.02 per request with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —USDC asset contract on Base: 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/cards/50/transactions