x402-gated card transaction endpoint on Base, pay $0.02 per request in USDC.
What it does
This endpoint at lowpaymentfee.com provides access to a card transactions resource at `/api/v1/cards/55/transactions` via the x402 payment protocol. It is part of a broader platform that offers numerous 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 targets card transaction data (card ID 55). It accepts HTTP POST requests and returns JSON. Payment is handled inline via the x402 protocol: callers attach an `X-PAYMENT` header containing a signed USDC payment of up to 20,000 base units ($0.02, since USDC uses 6 decimals) on Base. No API keys, accounts, or rate limits are advertised — access is purely payment-gated.
Documentation on the site is extremely sparse. The docs, pricing, API, and README pages all render only a "Connect wallet" prompt with no further content. There is no OpenAPI spec, no request/response schema documentation, and no usage examples available from the crawled material. The endpoint is live (returns a valid 402 challenge), but the actual functionality, required POST body fields, and response format for this card transactions endpoint are unknown from the available sources.
Capabilities
Use cases
- —Retrieving transaction data for a specific card via pay-per-call access
- —Integrating card transaction lookups into agent workflows without API key management
- —Programmatic access to card transaction records settled via on-chain USDC micropayments
Fit
Best for
- —Developers wanting zero-signup, pay-per-use card transaction data
- —AI agents that can settle x402 payments autonomously on Base
- —Prototyping integrations where traditional API key provisioning is undesirable
Not for
- —Production use cases requiring documented request/response schemas and SLAs
- —Bulk or high-volume transaction data retrieval where per-call pricing is inefficient
- —Users without a Base-network USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/cards/55/transactions \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <signed-x402-payment-header>"Endpoint
Quality
The endpoint is live and returns a valid x402 402 challenge, confirming it exists and accepts payments. However, there is no documentation, no OpenAPI spec, no request/response schema, and no examples. The description 'Premium API Access' is generic and uninformative. The docs pages are empty. The actual purpose and data returned by this card transactions endpoint can only be guessed from the URL path.
Warnings
- —No documentation available — docs, pricing, API, and README pages all show only 'Connect wallet' with no content.
- —No request body schema or response schema documented; callers cannot know what fields to send or expect.
- —The endpoint path '/api/v1/cards/55/transactions' with a hardcoded card ID 55 is unusual and unexplained.
- —The 'Premium API Access' description is generic and does not describe what this specific endpoint does.
- —This endpoint is not listed among the advertised APIs on the homepage, raising questions about its intended use.
Citations
- —The platform advertises $0.02 per request pricing with no API keys, no rate limits, and instant access on the Base network.https://lowpaymentfee.com
- —The x402 challenge specifies maxAmountRequired of 20000 base units of USDC (asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Base network.https://lowpaymentfee.com/api/v1/cards/55/transactions
- —Docs, pricing, API, and README pages render only a 'Connect wallet' prompt with no further content.https://lowpaymentfee.com/docs