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/98/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 a specified wallet address. The endpoint accepts HTTP POST requests and returns application/json responses.
The broader lowpaymentfee.com platform advertises a suite of pay-per-request APIs spanning data & analytics, AI/ML inference (sentiment analysis, summarization, classification, embeddings), finance & Web3 (price feeds, exchange rates, token quotes, gas estimates), and infrastructure utilities (geocoding, validation, conversion, generation). All endpoints are listed at $0.02 per request with no API keys, no rate limits, and no minimum commitments — payment is handled entirely via the x402 protocol using USDC on Base.
However, the specific endpoint being listed here (`/api/v1/cards/98/transactions`) does not appear in the site's published API catalog, and no documentation, request schema, or response schema is available for it. The "Premium API Access" description from the x402 challenge is generic and does not clarify what data or functionality this particular endpoint provides. Without documentation or example payloads, the actual purpose of this card-transactions resource is unclear — it may relate to financial card transaction data, but this is speculative.
Capabilities
Use cases
- —Retrieving or submitting card transaction data via a single paid API call
- —Integrating pay-per-request card transaction lookups into agent workflows
- —Programmatic access to card-level transaction records without API key management
Fit
Best for
- —Agents that can settle x402 payments in USDC on Base
- —Use cases requiring no-signup, pay-per-call access to card transaction data
- —Developers wanting to avoid API key management and rate limit negotiations
Not for
- —Users who need detailed documentation or guaranteed SLAs before integrating
- —High-volume batch processing where per-request pricing is cost-prohibitive
- —Anyone unable to settle USDC payments on the Base network
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/cards/98/transactions \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-header>" \
-d '{}'Endpoint
Quality
The x402 challenge is live and confirms pricing ($0.02 USDC on Base), but the specific endpoint is undocumented — it does not appear in the site's published catalog, and no request/response schema, examples, or description beyond the generic 'Premium API Access' label are available. Docs pages returned only 'Connect wallet' with no content.
Warnings
- —This specific endpoint (/api/v1/cards/98/transactions) is not listed in the site's published API catalog — its purpose is unclear.
- —No request or response schema is documented; the outputSchema in the challenge only specifies HTTP POST.
- —All documentation pages (/docs, /api, /pricing, /README) returned only 'Connect wallet' with no substantive content.
- —The endpoint's actual functionality (what card transactions data it returns or accepts) is entirely unverified.
Citations
- —The x402 challenge requests up to 20,000 base units of USDC (asset 0x8335…) on Base network, equaling $0.02.https://lowpaymentfee.com/api/v1/cards/98/transactions
- —The site advertises $0.02/request pricing with no API keys, no rate limits, and instant access on Base network.https://lowpaymentfee.com
- —The site lists APIs across data & analytics, AI/ML, finance & Web3, and infrastructure categories.https://lowpaymentfee.com
- —Documentation pages (/docs, /api, /pricing, /README) returned only 'Connect wallet' with no substantive content.https://lowpaymentfee.com/docs