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/38/transactions` behind the x402 payment protocol. When called without payment, it returns a 402 challenge requiring a USDC payment on the Base network. The maximum amount required per call is 20,000 base units of USDC (0.02 USD), settled to the specified payTo address.
The hosting site lowpaymentfee.com advertises a broad catalog 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 commitments — payment is handled entirely via the x402 protocol on Base.
However, the specific endpoint being listed here (`/api/v1/cards/38/transactions`) is not explicitly documented on the site's landing page among the advertised APIs. Its title "Premium API Access" and its path suggest it relates to card transaction data for a specific card (ID 38), but no schema, request format, or response format documentation is available. The docs, pricing, and API pages all render only a "Connect wallet" prompt with no further content. Without documentation on what this endpoint accepts or returns, usage requires experimentation or direct knowledge of the API contract.
Capabilities
Use cases
- —Retrieving transaction history for a specific card via programmatic pay-per-call access
- —Integrating card transaction data into agent workflows that support x402 payments
- —Demonstrating x402 protocol usage for micropayment-gated API access
Fit
Best for
- —Developers experimenting with x402 payment protocol on Base
- —Agents that can autonomously settle USDC micropayments for API access
- —Use cases needing keyless, per-request API access without subscriptions
Not for
- —Production workloads requiring documented request/response schemas
- —Users who need traditional API-key-based authentication
- —High-volume batch processing where per-request fees add up
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/cards/38/transactions
# Returns 402 with x402 challenge; include X-PAYMENT header with valid USDC payment proof to access.Endpoint
Quality
The endpoint is live (402 challenge captured) and pricing is clear ($0.02 USDC on Base), but there is no documentation on request/response schemas, no OpenAPI spec, and the specific endpoint path is not listed among the site's advertised APIs. Docs pages render only a wallet-connect prompt. This is effectively a stub listing.
Warnings
- —No request or response schema documentation available for this specific endpoint
- —The endpoint path /api/v1/cards/38/transactions is not listed among the site's publicly advertised APIs
- —All documentation pages (docs, pricing, API, README) render only a 'Connect wallet' prompt with no content
- —The purpose and data returned by this endpoint are unclear — 'Premium API Access' is a generic label
Citations
- —The x402 challenge requires maxAmountRequired of 20000 base units of USDC (asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Base networkhttps://lowpaymentfee.com/api/v1/cards/38/transactions
- —The site advertises all endpoints at $0.02 per request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —Docs, pricing, API, and README pages show only a 'Connect wallet' prompthttps://lowpaymentfee.com/docs