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/59/transactions` behind the x402 payment protocol. When called without payment, it returns a 402 challenge requesting up to 20,000 base units of USDC (0.02 USD) on the Base network, settled to address `0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3`. The payment scheme is "exact" with a 300-second timeout.
The provider site (lowpaymentfee.com) advertises a broad catalog of pay-per-request 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 priced at $0.02 per request with no API keys, no rate limits, and no commitments. However, the specific endpoint being listed here (`/api/v1/cards/59/transactions`) does not appear in the site's published catalog and its description is simply "Premium API Access," so the actual data returned by this endpoint is unclear. No OpenAPI schema, request/response examples, or detailed documentation were found in the crawl.
Because the endpoint's purpose and response format are undocumented, agents should treat this as an exploratory integration. The x402 challenge is live and well-formed, confirming the endpoint is operational, but the lack of documentation about what "card 59 transactions" means or what fields the response contains is a significant gap.
Capabilities
Use cases
- —Fetching transaction data for a specific card resource via x402 payment
- —Integrating pay-per-request card transaction lookups into agent workflows
- —Exploring x402 protocol-based API consumption on Base
Fit
Best for
- —Developers experimenting with x402 payment protocol
- —Agents that can settle USDC on Base for per-call API access
- —Use cases needing keyless, pay-as-you-go API access
Not for
- —Production systems requiring well-documented request/response schemas
- —Users who need free or subscription-based API access
- —Applications requiring high-throughput batch transaction queries
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/cards/59/transactions
# Returns 402 with x402 challenge; attach X-PAYMENT header with USDC payment proof on Base to access.Endpoint
Quality
The x402 challenge is live and well-formed, confirming the endpoint works. However, this specific endpoint is not listed in the provider's own catalog, there is no OpenAPI schema, no request/response examples, and no documentation explaining what data it returns. Effectively a stub listing.
Warnings
- —Endpoint /api/v1/cards/59/transactions is not listed in the provider's published API catalog — its purpose is unclear.
- —No OpenAPI schema or request/response documentation found.
- —Docs, pricing, API, and README pages all returned only 'Connect wallet' with no substantive content.
- —The meaning of 'cards/59/transactions' is undocumented; it may be a demo or placeholder resource.
Citations
- —The x402 challenge requests up to 20,000 base units of USDC (0.02 USD) on Base network with scheme 'exact' and 300-second timeout.https://lowpaymentfee.com/api/v1/cards/59/transactions
- —The provider advertises all APIs at $0.02 per request with no API keys, no rate limits, and instant access on Base network.https://lowpaymentfee.com
- —USDC asset address is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base.https://lowpaymentfee.com/api/v1/cards/59/transactions