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/30/transactions` behind an x402 paywall. It accepts POST requests and is settled on the Base network using USDC (contract 0x8335…2913). The per-request cost is $0.02 (20,000 base units of USDC with 6 decimals). No API keys or rate limits are required — callers simply attach an X-PAYMENT header with a valid x402 payment proof.
The broader lowpaymentfee.com platform advertises a wide 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 share the same $0.02/request pricing model and x402 payment flow on Base.
Documentation is extremely sparse — the /docs, /pricing, /api, and /README pages all render only a "Connect wallet" prompt with no further technical detail. There is no OpenAPI spec, no request/response schema, and no usage examples available from the crawl. The specific purpose of the `/api/v1/cards/30/transactions` endpoint (what "card 30" refers to, what data it returns or accepts) is not documented anywhere in the crawled material. Callers should treat this as an exploratory integration until more documentation surfaces.
Capabilities
Use cases
- —Querying or posting card transaction data via a pay-per-call model
- —Integrating x402 payment flows into agent-driven workflows
- —Accessing financial card data without traditional API key provisioning
Fit
Best for
- —Developers experimenting with x402 payment protocol on Base
- —Agents that need keyless, pay-as-you-go API access
- —Low-volume consumers who want no subscription commitments
Not for
- —Production workloads requiring documented request/response schemas
- —High-volume use cases where per-request pricing may add up
- —Users who need detailed API documentation before integrating
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/cards/30/transactions \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-proof>"Endpoint
Quality
The endpoint is live (402 challenge captured) and pricing is clear ($0.02/request in USDC on Base), but there is no OpenAPI spec, no request/response schema, no documentation beyond a wallet-connect prompt, and the specific function of this card-transactions endpoint is undocumented. This is effectively a stub listing.
Warnings
- —No OpenAPI or schema available — request and response formats are unknown
- —All documentation pages (/docs, /pricing, /api, /README) render only 'Connect wallet' with no technical content
- —The purpose of '/api/v1/cards/30/transactions' (what 'card 30' means, what data is returned) is not documented anywhere
- —The broader platform advertises many endpoints but none have visible documentation
Citations
- —Endpoint returns HTTP 402 with x402 challenge, accepting USDC on Base networkhttps://lowpaymentfee.com/api/v1/cards/30/transactions
- —maxAmountRequired is 20000 base units of USDC (6 decimals) = $0.02 per requesthttps://lowpaymentfee.com/api/v1/cards/30/transactions
- —Platform advertises $0.02/request pricing with no API keys, no rate limits, and instant access on Basehttps://lowpaymentfee.com
- —Documentation pages render only 'Connect wallet' with no technical contenthttps://lowpaymentfee.com/docs