x402-gated card-transactions endpoint on Base, pay $0.02 per request in USDC.
What it does
This endpoint at lowpaymentfee.com exposes a card-transactions resource at `/api/v1/cards/53/transactions` behind an x402 payment challenge. It is part of a broader platform that offers dozens of 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 appears to relate to card transaction data (card ID 53). The x402 challenge confirms the endpoint is live, accepting POST requests, and requiring an exact-scheme payment of 20,000 base-unit USDC (i.e., $0.02 given USDC's 6 decimals) to the address `0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3`. The asset contract `0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913` is the canonical USDC contract on Base. No API keys or rate limits are advertised; access is granted purely via the x402 payment header.
Documentation is extremely sparse. The docs, API, pricing, and README pages all render only a "Connect wallet" prompt with no further content. There is no OpenAPI schema, no request/response examples, and no description of what fields the transactions endpoint accepts or returns. The platform's landing page confirms the pricing model and lists many endpoints, but provides no technical detail about request formats or response payloads for any of them.
Capabilities
Use cases
- —Retrieving transaction history for a specific card via a single paid API call
- —Integrating card transaction data into an agent workflow without managing API keys
- —Programmatic access to card-level transaction records settled via crypto micropayments
Fit
Best for
- —Agents or services that need card transaction data and can pay per-call in USDC on Base
- —Developers who want keyless, pay-as-you-go API access
- —Workflows requiring x402-compatible payment-gated endpoints
Not for
- —Users who need detailed API documentation or response schemas before integrating
- —High-volume use cases where per-request pricing may add up without bulk discounts
- —Anyone without a Base-compatible USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/cards/53/transactions \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live and returns a valid x402 challenge with clear pricing, but there is zero documentation on request/response schemas, no OpenAPI spec, and all doc pages render only 'Connect wallet'. The purpose of the specific card-transactions endpoint is unclear beyond its URL path.
Warnings
- —No API documentation available — all doc pages render only 'Connect wallet'
- —No OpenAPI or request/response schema provided
- —The purpose and data returned by /api/v1/cards/53/transactions is entirely unclear
- —The card ID '53' is hardcoded in the URL with no explanation of what it represents
- —Platform lists many endpoints but none have technical documentation
Citations
- —The endpoint returns a 402 x402 challenge with maxAmountRequired of 20000 base-unit USDC on Basehttps://lowpaymentfee.com/api/v1/cards/53/transactions
- —All APIs are priced at $0.02 per request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —The USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/cards/53/transactions