Pay-per-call API access on Base via x402 — $0.02/request in USDC, no keys required.
What it does
lowpaymentfee.com offers a collection of pay-per-request API endpoints accessible via the x402 payment protocol on the Base network. Each call costs $0.02 in USDC (USD Coin), settled on-chain with no API keys, rate limits, or upfront commitments required.
The specific endpoint `/api/v1/keys/39` is listed as "Premium API Access" and returns an x402 challenge requesting up to 20,000 base units of USDC (0x8335…2913 on Base), which equals $0.02 given USDC's 6 decimals. Payment is made via the `exact` scheme with a 300-second timeout. The broader platform advertises endpoints across four categories: Data & Analytics (metrics, reports, data export, insights), AI & Machine Learning (sentiment analysis, text summarization, classification, embeddings), Finance & Web3 (price feeds, exchange rates, token quotes, gas estimates), and Infrastructure utilities (geocoding, validation, conversion, generation).
Documentation is minimal — the site's /api, /pricing, and /README pages all resolve to a "Connect wallet" prompt with no further content. There is no OpenAPI spec, no request/response schema documentation, and no usage examples available. The endpoint is confirmed live (402 challenge captured), but without documentation it is unclear what input this specific endpoint expects or what it returns beyond `application/json`.
Capabilities
Use cases
- —Accessing premium API endpoints without managing API keys or subscriptions
- —Making one-off paid API calls settled instantly on Base in USDC
- —Agent-driven workflows that need on-demand API access with crypto payment
Fit
Best for
- —Developers who want keyless, pay-as-you-go API access
- —AI agents with USDC on Base that need to call APIs autonomously
- —Users who prefer per-request billing over subscription plans
Not for
- —Users who need detailed API documentation or OpenAPI specs before integrating
- —High-volume use cases where $0.02/request adds up significantly
- —Users without a Base-compatible wallet or USDC holdings
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/keys/39 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is confirmed live with a valid x402 402 challenge, but there is no OpenAPI spec, no request/response schema, no documentation beyond a landing page listing, and no examples. The purpose of this specific endpoint (/api/v1/keys/39) is unclear. Pricing is clear ($0.02) but everything else must be inferred.
Warnings
- —No OpenAPI or schema documentation available — input/output format for this endpoint is unknown
- —The /api, /pricing, and /README pages all return only a 'Connect wallet' prompt with no useful content
- —The specific purpose of /api/v1/keys/39 ('Premium API Access') is not explained anywhere
- —No request or response examples are available
Citations
- —The endpoint returns a 402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/keys/39
- —USDC contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/keys/39
- —The platform advertises $0.02/request pricing with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —Available API categories include Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructurehttps://lowpaymentfee.com