Pay-per-call API platform on Base via x402 — $0.02/request, no API keys required.
What it does
lowpaymentfee.com is a pay-per-request API platform that uses the x402 protocol to accept USDC payments on the Base network. The specific endpoint at `/api/v1/payments/243` is labeled "Premium API Access" and charges up to $0.02 per call (20,000 base units of USDC with 6 decimals). The platform advertises no API keys, no rate limits, and instant access — callers simply attach an X-PAYMENT header with a valid x402 payment proof.
The broader platform offers 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). All endpoints are listed at $0.02 per request.
This particular endpoint (`/api/v1/payments/243`) is live and returned a proper 402 challenge when probed. However, the crawled documentation pages (docs, pricing, API, README) all returned only a "Connect wallet" prompt with no substantive content, so the actual functionality behind this specific endpoint is unclear. There is no OpenAPI schema, no request/response examples, and no detailed documentation available from the crawl.
Capabilities
Use cases
- —Accessing premium API endpoints without traditional API key registration
- —Making one-off API calls paid per request via USDC on Base
- —Agent-driven workflows that need frictionless, keyless API access
Fit
Best for
- —Developers who want pay-as-you-go API access without subscriptions
- —AI agents that can settle x402 payments autonomously
- —Users already holding USDC on the Base network
Not for
- —Users who need detailed API documentation or OpenAPI specs before integrating
- —High-volume callers who would benefit from bulk pricing or subscriptions
- —Developers without access to USDC on the Base network
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/payments/243 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-proof>"Endpoint
Quality
The endpoint is live and returns a valid x402 402 challenge, but there is no OpenAPI schema, no documentation content (all doc pages show only 'Connect wallet'), no request/response examples, and the actual functionality behind '/api/v1/payments/243' is not described anywhere. The listing is effectively a stub.
Warnings
- —No documentation available — all doc/pricing/API/README pages returned only 'Connect wallet' with no content.
- —The specific functionality of /api/v1/payments/243 ('Premium API Access') is not described; it is unclear what this endpoint actually does.
- —No OpenAPI schema or request/response examples are provided.
- —The platform lists many endpoint categories (AI, finance, analytics, infrastructure) but none have documented schemas or verifiable functionality.
Citations
- —The endpoint returns a 402 challenge with maxAmountRequired of 20000 base units of USDC on Base networkhttps://lowpaymentfee.com/api/v1/payments/243
- —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
- —USDC asset address is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/payments/243