x402-gated card-transaction endpoint on Base, pay-per-call with USDC.
What it does
This endpoint at lowpaymentfee.com exposes a card transactions resource at `/api/v1/cards/10/transactions` behind an x402 payment challenge. The endpoint accepts POST requests and is settled on the Base network using USDC (contract 0x8335…2913). The per-call cost is 20,000 base units of USDC, which with 6 decimals equals $0.02 per request.
The provider site lowpaymentfee.com advertises a broad catalog of pay-per-call APIs spanning data & analytics, AI/ML (sentiment, summarization, classification, embeddings), finance & Web3 (price feeds, exchange rates, token quotes, gas estimates), and infrastructure utilities (geocoding, validation, conversion, generation) — all at $0.02 per request. The specific endpoint listed here (`/api/v1/cards/10/transactions`) is labeled "Premium API Access" but does not appear in the site's public catalog, and no documentation describes its request or response schema. The site's docs, pricing, and API pages all render only a "Connect wallet" prompt with no further content.
Because there is no OpenAPI spec, no request/response schema documentation, and no description of what "card transactions" means in this context, the actual functionality of this endpoint is unclear. It could relate to financial card transaction data, but this is speculative. The x402 challenge is live and well-formed, confirming the endpoint is operational and accepting payments on Base.
Capabilities
Use cases
- —Retrieving or submitting card transaction data via a pay-per-call model
- —Integrating x402-compatible payment flows into agent workflows
- —Accessing financial transaction records without API key registration
Fit
Best for
- —Agents or developers already using x402 payment protocol on Base
- —Use cases requiring keyless, per-request API access
- —Scenarios where USDC micropayments are preferred over subscription billing
Not for
- —Users who need documented request/response schemas before integration
- —High-volume use cases where per-call pricing at $0.02 adds up significantly
- —Anyone needing clear regulatory or compliance documentation for financial data
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/cards/10/transactions \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-header>" \
-d '{}'Endpoint
Quality
The x402 challenge is live and well-formed, confirming the endpoint is operational. However, there is no OpenAPI spec, no request/response schema, no documentation beyond a wallet-connect prompt, and the specific endpoint does not appear in the provider's own catalog. Functionality is essentially unknown.
Warnings
- —No request or response schema documented anywhere
- —This specific endpoint (/api/v1/cards/10/transactions) is not listed in the provider's public API catalog
- —All documentation pages (docs, pricing, API, README) render only 'Connect wallet' with no content
- —The meaning of 'card transactions' in this context is unclear — could be financial data or something else entirely
- —No OpenAPI or ai-plugin manifest available
Citations
- —The x402 challenge returns status 402 with maxAmountRequired 20000 in USDC on Base networkhttps://lowpaymentfee.com/api/v1/cards/10/transactions
- —USDC asset contract is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/cards/10/transactions
- —The provider advertises $0.02 per request across all APIs with no API keys, no rate limitshttps://lowpaymentfee.com
- —Docs, pricing, API, and README pages all show only 'Connect wallet'https://lowpaymentfee.com/docs