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/91/transactions` behind the x402 payment protocol. When called without payment, it returns a 402 challenge requiring a USDC payment on the Base network. The maximum amount required per call is 20,000 base units of USDC (0.02 USD), settled to a specified wallet address. The endpoint accepts HTTP POST requests and returns application/json.
The broader lowpaymentfee.com platform advertises a suite of pay-per-request APIs spanning data analytics, AI/ML inference (sentiment analysis, summarization, classification, embeddings), finance/crypto data feeds, and infrastructure utilities — all priced at $0.02 per request with no API keys, no rate limits, and no commitments. However, the specific endpoint being listed here (`/api/v1/cards/91/transactions`) is not explicitly documented on the site's landing page among the advertised APIs, and its exact functionality (what "card 91 transactions" means or returns) is unclear from the available material.
Payment is handled via the x402 exact scheme: callers attach an X-PAYMENT header with a signed USDC payment on Base. The asset contract is the canonical Base USDC (0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913). The endpoint is live and responding with a valid 402 challenge.
Capabilities
Use cases
- —Retrieving transaction data for a specific card via a single paid API call
- —Integrating pay-per-request card transaction lookups into agent workflows
- —Programmatic access to card transaction records without API key management
Fit
Best for
- —Agents needing on-demand card transaction data with crypto micropayments
- —Developers who want keyless, pay-as-you-go API access on Base
- —Workflows requiring x402-compatible endpoints
Not for
- —Users needing bulk/batch transaction exports at scale (no documented batch mode)
- —Anyone without a Base-network USDC wallet
- —Use cases requiring detailed API documentation or guaranteed SLAs
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/cards/91/transactions \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <signed-x402-payment-header>"Endpoint
Quality
The endpoint is live and returns a valid x402 402 challenge, but there is no documentation on what this specific endpoint does, what request body it expects, or what it returns. The endpoint path (/api/v1/cards/91/transactions) is not listed among the site's advertised APIs. No OpenAPI spec, no examples, and crawled docs/pricing/api pages are empty beyond a 'Connect wallet' prompt.
Warnings
- —This specific endpoint (/api/v1/cards/91/transactions) is not listed among the provider's advertised APIs — its purpose and response format are unknown.
- —No API documentation, OpenAPI spec, or request/response examples are available.
- —The docs, pricing, API, and README pages all returned only 'Connect wallet' with no usable content.
- —The meaning of 'cards/91/transactions' is unclear — it may be a demo, placeholder, or internal resource.
Citations
- —The endpoint returns a 402 challenge requiring USDC payment of 20000 base units (0.02 USD) on Base networkhttps://lowpaymentfee.com/api/v1/cards/91/transactions
- —The USDC asset contract is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/cards/91/transactions
- —The platform advertises $0.02/request pricing with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —The site lists APIs for analytics, AI/ML, finance, and infrastructure but does not list /api/v1/cards/91/transactionshttps://lowpaymentfee.com