x402-gated premium API endpoint on Base, pay $0.02 per request in USDC.
What it does
This endpoint at `/api/v1/cards/97` is part of the lowpaymentfee.com platform, which offers a collection of x402-protocol pay-per-request APIs spanning data & analytics, AI & machine learning, finance & Web3, and infrastructure utilities. The specific resource at `/cards/97` is labeled "Premium API Access" but its exact functionality is not documented beyond that label. It is one of many endpoints on the platform, all priced uniformly at $0.02 per call.
Payment is handled via the x402 protocol on the Base network using USDC (contract `0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913`). The challenge advertises a `maxAmountRequired` of 20,000 base units, which at 6 decimals equals $0.02. No API keys or rate limits are required — callers simply attach an `X-PAYMENT` header with a valid x402 payment proof. The endpoint accepts HTTP POST requests and returns `application/json`.
The broader platform lists endpoints for sentiment analysis, text summarization, classification, embeddings, price feeds, exchange rates, geocoding, validation, conversion, and generation — all at the same $0.02 price point. However, documentation is extremely sparse: the docs, API, pricing, 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. The exact behavior of `/api/v1/cards/97` specifically is unknown.
Capabilities
Use cases
- —Accessing premium API data with per-request USDC micropayments
- —Agent-driven API consumption without API key management
- —Programmatic pay-as-you-go endpoint access on Base L2
Fit
Best for
- —Developers wanting keyless, pay-per-request API access
- —AI agents that can settle x402 payments on Base
- —Users who prefer crypto micropayments over subscription billing
Not for
- —Users needing detailed API documentation or schemas before integrating
- —Applications requiring free or subscription-based access
- —Anyone needing non-USDC or non-Base payment options
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/cards/97 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-proof>"Endpoint
Quality
The endpoint is live and returns a valid x402 402 challenge, confirming pricing and payment details. However, there is no documentation, no OpenAPI spec, no request/response schema, and no explanation of what '/api/v1/cards/97' actually does. The docs pages are empty beyond a wallet connect prompt. This is effectively a stub listing.
Warnings
- —The exact functionality of /api/v1/cards/97 ('Premium API Access') is completely undocumented — its purpose is unknown.
- —No OpenAPI spec, request schema, or response schema is available anywhere on the site.
- —All documentation pages (docs, API, pricing, README) render only 'Connect wallet' with no technical content.
- —The platform lists many endpoints but none have detailed documentation; integration requires trial and error.
Citations
- —The endpoint returns a 402 challenge with maxAmountRequired of 20000 base units in USDC on Basehttps://lowpaymentfee.com/api/v1/cards/97
- —USDC asset contract is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/cards/97
- —All endpoints are priced at $0.02 per request with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —The platform offers endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com
- —Docs, API, pricing, and README pages show only 'Connect wallet'https://lowpaymentfee.com/docs