x402-gated card-transactions endpoint on Base, paying per request in USDC.
What it does
This endpoint at lowpaymentfee.com exposes a POST resource at `/api/v1/cards/3/transactions` behind an x402 payment challenge. The x402 challenge advertises a maximum cost of 20,000 base units of USDC on the Base network. Since USDC uses 6 decimals, this translates to $0.02 per request. The provider's landing page confirms a flat $0.02/request pricing model across all its endpoints, with no API keys, no rate limits, and instant access.
The specific endpoint path (`/api/v1/cards/3/transactions`) suggests it deals with card transaction data — likely retrieving or creating transactions associated with a particular card resource (card ID 3). However, there is no OpenAPI schema, no request/response documentation, and no examples available from the crawl. The docs, pricing, and API pages all returned only a "Connect wallet" prompt with no further content. The provider's landing page lists many other endpoints across categories like Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructure, but this particular cards/transactions endpoint is not listed among them.
The endpoint is live and responds with a proper x402 v1 challenge. Payment is settled in USDC on the Base L2 network using the "exact" scheme. The payTo address is `0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3` and the USDC asset contract is `0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913`. The timeout for payment is 300 seconds.
Capabilities
Use cases
- —Retrieving or creating card transaction records via a pay-per-call model
- —Integrating card transaction data into agent workflows without API key management
- —Programmatic access to card-level transaction information settled in USDC on Base
Fit
Best for
- —Agents needing card transaction data with zero signup friction
- —Developers who prefer crypto micropayments over traditional API key billing
- —x402-compatible clients on the Base network
Not for
- —Users who need detailed API documentation or request/response schemas before integrating
- —High-volume use cases where per-request pricing at $0.02 may be cost-prohibitive compared to subscription plans
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/cards/3/transactions \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-header>" \
-d '{}'Endpoint
Quality
The endpoint is live and returns a valid x402 challenge, confirming pricing and network details. However, there is no documentation, no request/response schema, no examples, and the specific endpoint is not even listed on the provider's own landing page. The docs pages are empty beyond a wallet-connect prompt. This is effectively a stub listing.
Warnings
- —No API documentation available — docs, pricing, and API pages all show only 'Connect wallet' with no content
- —No request body schema or response schema provided; callers cannot know what to send or expect back
- —The /api/v1/cards/3/transactions endpoint is not listed among the provider's advertised APIs on the landing page
- —The endpoint path references a hardcoded card ID (3), which may indicate a demo or placeholder resource
Citations
- —The x402 challenge advertises maxAmountRequired of 20000 base units of USDC on Base networkhttps://lowpaymentfee.com/api/v1/cards/3/transactions
- —USDC asset contract is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/cards/3/transactions
- —Provider advertises $0.02/request flat pricing with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com