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/37/transactions` behind an x402 payment challenge. It is part of a broader platform that offers dozens of pay-per-call APIs spanning data analytics, AI/ML inference, finance/Web3 data, and infrastructure utilities — all priced at $0.02 per request and settled in USDC on the Base network.
The specific endpoint listed here appears to relate to card transaction data (card ID 37). The x402 challenge confirms it accepts POST requests, requires up to 20,000 base units of USDC (i.e., $0.02 given USDC's 6 decimals) paid to address `0x1A2B…85F3`, and returns `application/json`. No API keys or rate limits are advertised; access is granted purely through the x402 payment header.
Documentation on the site is extremely thin — the docs, API, pricing, and README pages all render only a "Connect wallet" prompt with no substantive content. There is no OpenAPI schema, no request/response examples, and no description of what fields the card-transactions endpoint accepts or returns. The endpoint is live (returns a proper 402 challenge), but the lack of documentation makes it difficult to know what payload to send or what response to expect.
Capabilities
Use cases
- —Retrieving transaction data for a specific card via a pay-per-call model
- —Programmatic access to card transaction records without API key management
- —Agent-driven financial data retrieval settled in USDC on Base
Fit
Best for
- —Developers wanting keyless, pay-per-use card transaction data
- —AI agents that can settle x402 payments on Base
- —Prototyping financial data integrations without subscription commitments
Not for
- —Production use requiring documented request/response schemas
- —High-volume batch retrieval where per-call pricing is inefficient
- —Users who need non-crypto payment options
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/cards/37/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 zero documentation on request format, response schema, or what 'cards/37/transactions' actually returns. Docs pages are empty. No OpenAPI spec, no examples, no field descriptions. This is effectively a stub listing.
Warnings
- —No documentation available — docs, API, pricing, and README pages all show only 'Connect wallet' with no content.
- —No OpenAPI or request/response schema provided; callers cannot know what payload to send.
- —The specific resource '/api/v1/cards/37/transactions' is not listed on the site's own homepage API catalog, raising questions about its intended use.
- —Card ID '37' is hardcoded in the URL; unclear if other card IDs are valid or how to discover them.
Citations
- —The endpoint returns a 402 challenge requiring USDC payment of 20000 base units (=$0.02) on Base network.https://lowpaymentfee.com/api/v1/cards/37/transactions
- —The platform advertises $0.02/request pricing with no API keys, no rate limits, and instant access on Base network.https://lowpaymentfee.com
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913.https://lowpaymentfee.com/api/v1/cards/37/transactions