x402-gated card-transactions endpoint on Base, pay $0.02 per request in USDC.
What it does
This endpoint at lowpaymentfee.com exposes a card-transactions resource at `/api/v1/cards/75/transactions` behind the x402 payment protocol. It accepts POST requests and requires an X-PAYMENT header carrying a USDC payment on the Base network. The x402 challenge advertises a maximum amount of 20,000 base units of USDC (0x8335…2913 on Base), which equals $0.02 per request (USDC uses 6 decimals). The endpoint is described generically as "Premium API Access" with no further documentation on the request body schema or response format.
The provider, lowpaymentfee.com, hosts a broader catalog of x402-gated APIs spanning data analytics, AI/ML inference, finance/Web3 data, and infrastructure utilities — all priced at $0.02 per call with no API keys, no rate limits, and no minimum commitments. However, the specific `/api/v1/cards/75/transactions` endpoint is not listed on the provider's landing page among the advertised APIs, and no dedicated documentation, request/response examples, or OpenAPI schema were found during crawling. The docs, pricing, and API pages all returned only a "Connect wallet" prompt with no additional content.
Because the endpoint's actual functionality is unclear — the path suggests card transaction data but no schema or sample payloads are available — agents should treat this as a low-documentation endpoint. The x402 challenge is live and well-formed, confirming the endpoint is operational and accepts payments, but what it returns after payment remains unverified.
Capabilities
Use cases
- —Retrieving card transaction data via a pay-per-request model
- —Programmatic access to card-level transaction records without API key management
- —Agent-driven financial data retrieval settled in USDC on Base
Fit
Best for
- —Agents that can settle x402 payments in USDC on Base
- —Use cases needing keyless, per-call access to card transaction data
- —Developers exploring x402 protocol integrations
Not for
- —Users who need detailed API documentation or guaranteed response schemas before integrating
- —High-volume batch processing where per-call pricing may add up
- —Anyone unable to transact in USDC on the Base network
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/cards/75/transactions \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-header>"Endpoint
Quality
The x402 challenge is live and well-formed, confirming the endpoint is operational. However, there is no OpenAPI schema, no request/response examples, no documentation beyond a generic title, and the specific endpoint is not even listed on the provider's own landing page. Effectively a stub.
Warnings
- —No request body schema or response schema available — actual functionality is unknown
- —Endpoint path /api/v1/cards/75/transactions is not listed among the provider's advertised APIs
- —All documentation pages (docs, pricing, API, README) returned only a 'Connect wallet' prompt with no content
- —The hardcoded card ID '75' in the path suggests this may be a specific resource rather than a general-purpose API
Citations
- —x402 challenge returns maxAmountRequired of 20000 base units of USDC on Base networkhttps://lowpaymentfee.com/api/v1/cards/75/transactions
- —Provider advertises $0.02 per request across all APIs with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —USDC asset address is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/cards/75/transactions
- —Docs, pricing, API, and README pages returned only 'Connect wallet' with no additional contenthttps://lowpaymentfee.com/docs