x402-gated card-transactions 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/78/transactions` behind an x402 payment challenge. It accepts HTTP POST requests and requires an X-PAYMENT header carrying a USDC payment on the Base network. The maximum amount required per call is 20,000 base units of USDC (0.02 USD, since USDC uses 6 decimals), consistent with the site-wide $0.02/request pricing advertised on the provider's landing page.
The provider, lowpaymentfee.com, hosts a broad catalog of x402-gated APIs spanning data analytics, AI/ML inference, finance/Web3 data, and infrastructure utilities — all at the same $0.02 per request price point. This specific endpoint appears to be a card-transactions resource (path includes `/cards/78/transactions`), but no detailed documentation, request schema, or response schema is available. The docs, pricing, API, and README pages all resolve to a minimal "Connect wallet" prompt with no further content.
Because there is no OpenAPI spec, no request/response examples, and no documentation beyond the landing page listing, the actual behavior of this endpoint is unclear. It is live (returns a valid 402 challenge), but consumers should be aware that the lack of documentation makes integration speculative. The endpoint settles payments to `0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3` using the USDC contract `0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913` on Base.
Capabilities
Use cases
- —Fetching card transaction records via a pay-per-call model
- —Integrating card transaction data into agent workflows without API keys
- —Programmatic access to card transaction information settled in USDC on Base
Fit
Best for
- —Agents or apps needing card transaction data without subscription commitments
- —Developers who prefer crypto-native pay-per-request billing
- —Low-volume or sporadic access to card transaction records
Not for
- —Users who need detailed API documentation or response schemas before integrating
- —High-volume consumers who would benefit from bulk pricing or subscriptions
- —Anyone requiring non-crypto payment methods
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/cards/78/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 no OpenAPI spec, no request/response schema, no documentation, and no examples. The actual purpose and data returned by this card-transactions endpoint are entirely unclear.
Warnings
- —No API documentation available — docs, pricing, API, and README pages all show only a 'Connect wallet' prompt
- —No request or response schema provided; integration is speculative
- —The specific resource '/api/v1/cards/78/transactions' is not listed on the provider's landing page catalog, raising questions about its intended use
- —No OpenAPI or ai-plugin manifest found
Citations
- —The endpoint returns a 402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/cards/78/transactions
- —Site-wide pricing is $0.02 per request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/cards/78/transactions