x402-gated card transaction endpoint on Base, pay-per-call with USDC.
What it does
This endpoint at lowpaymentfee.com provides access to a card transactions resource at `/api/v1/cards/23/transactions` via the x402 payment protocol. The endpoint is live and returns a standard 402 challenge requiring payment in USDC on the Base network. The maximum amount required per call is 20,000 base units of USDC (6 decimals), which equals $0.02 per request.
The hosting site lowpaymentfee.com advertises a broad catalog of pay-per-call 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 settling in USDC on Base.
However, the specific endpoint being listed here (`/api/v1/cards/23/transactions`) is not explicitly documented on the site's landing page among the advertised APIs. Its description in the x402 challenge is simply "Premium API Access" with no further detail on the request body schema, expected response format, or what "card 23 transactions" refers to. The docs, pricing, and API pages all render only a "Connect wallet" prompt with no additional documentation. As a result, the actual functionality of this particular endpoint remains unclear.
Capabilities
Use cases
- —Retrieving transaction data for a specific card via pay-per-call USDC payments
- —Integrating x402-compatible agents with financial transaction endpoints
- —Programmatic access to card transaction records without API key management
Fit
Best for
- —Agents that support x402 payment protocol on Base
- —Developers wanting keyless, pay-per-call access to transaction data
- —Crypto-native applications settling microtransactions in USDC
Not for
- —Users needing detailed API documentation or schema before integrating
- —Applications requiring free or subscription-based access
- —Use cases needing bulk/batch transaction queries at scale
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/cards/23/transactions \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-header>"Endpoint
Quality
The endpoint is live (402 challenge confirmed) and pricing is clear ($0.02/request in USDC on Base), but there is no documentation for this specific endpoint, no request/response schema, and the crawled docs pages are empty. The endpoint path suggests card transaction data but its actual functionality is unverified.
Warnings
- —The specific endpoint /api/v1/cards/23/transactions is not listed among the site's advertised APIs
- —No request body schema or response schema is documented anywhere
- —All documentation pages (docs, pricing, API, README) render only 'Connect wallet' with no content
- —The purpose of 'cards/23/transactions' is unclear — it may be a demo or placeholder resource
Citations
- —The endpoint returns a 402 challenge with maxAmountRequired of 20000 base units of USDC on Base networkhttps://lowpaymentfee.com/api/v1/cards/23/transactions
- —The site advertises $0.02 per request with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —USDC asset contract 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/cards/23/transactions