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/83/transactions` behind the x402 payment protocol. It accepts HTTP POST requests and requires an X-PAYMENT header carrying a USDC payment on the Base network. The x402 challenge advertises a maximum cost of 20,000 base units of USDC (0x8335…), which equals $0.02 per request (USDC uses 6 decimals).
The broader lowpaymentfee.com platform lists multiple API categories — data & analytics, AI/ML inference, finance/Web3, and infrastructure utilities — all priced at $0.02 per request with no API keys, no rate limits, and no minimum commitments. However, the specific `/api/v1/cards/83/transactions` endpoint is not listed among the publicly advertised APIs on the landing page. Its exact functionality (what data it returns or what action it performs on "card 83 transactions") is undocumented. The description field in the x402 challenge simply reads "Premium API Access," which is generic and uninformative.
The endpoint is confirmed live: it returns a well-formed x402 version 1 challenge with a 402 status code. Payment settles in USDC on Base to address 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3. The timeout window is 300 seconds. No OpenAPI schema, request body schema, or response schema is provided, so callers cannot know what fields to send or what shape the response will take without experimentation.
Capabilities
Use cases
- —Retrieving or creating transactions associated with a specific card resource
- —Programmatic card transaction management via pay-per-call USDC payments
- —Agent-driven financial data access without API key registration
Fit
Best for
- —Developers wanting keyless, pay-per-call API access settled in USDC on Base
- —Agents that can handle x402 payment challenges natively
- —Users who need card transaction data without subscription commitments
Not for
- —Anyone needing documented request/response schemas before integration
- —High-volume use cases where per-call pricing may add up without volume discounts
- —Users without a Base-network USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/cards/83/transactions
# Returns 402 with x402 challenge; attach X-PAYMENT header with signed USDC payment to proceed.Endpoint
Quality
The endpoint is live and returns a valid x402 challenge, but there is no documentation on what the endpoint actually does, no request/response schema, and the specific path (/api/v1/cards/83/transactions) is not listed among the provider's advertised APIs. Effectively a stub with confirmed liveness.
Warnings
- —The endpoint path /api/v1/cards/83/transactions is not listed among the provider's publicly advertised APIs — its purpose is unclear.
- —No request body schema or response schema is available; callers must guess what to send.
- —Documentation pages (/docs, /api, /pricing, /README) all returned only a 'Connect wallet' prompt with no useful content.
- —The description 'Premium API Access' is generic and does not describe actual functionality.
Citations
- —The x402 challenge advertises maxAmountRequired of 20000 base units of USDC on Base networkhttps://lowpaymentfee.com/api/v1/cards/83/transactions
- —The platform advertises $0.02 per request, no API keys, no rate limits, instant access on Base networkhttps://lowpaymentfee.com
- —USDC contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/cards/83/transactions