Pay-per-call API platform on Base network via x402 — $0.02/request in USDC.
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 `/api/v1/transactions/205` is listed as "Premium API Access" and returns a 402 challenge requesting up to 20,000 base units of USDC (i.e., $0.02) per call. No API keys or rate limits are required; callers simply attach an x402 payment header to each request.
The broader platform advertises multiple API categories including 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 the same $0.02/request price point.
Documentation is extremely sparse — the docs, pricing, API, and README pages all render only a "Connect wallet" prompt with no further content. There is no OpenAPI schema, no request/response examples, and no description of what the `/api/v1/transactions/205` endpoint actually returns. The endpoint is live and responds with a valid x402 challenge, but without documentation it is unclear what data or functionality this specific transaction endpoint provides.
Capabilities
Use cases
- —Programmatic access to API services without managing API keys or subscriptions
- —Agent-driven workflows that need on-demand paid API calls settled in USDC on Base
- —Exploring x402 protocol integration for pay-per-use microservices
Fit
Best for
- —Developers experimenting with x402 payment protocol
- —Agents needing keyless, pay-as-you-go API access
- —Low-volume callers who want no subscription commitments
Not for
- —Production workloads requiring well-documented, schema-validated APIs
- —Users who need detailed request/response specifications before integrating
- —High-volume use cases where per-request pricing may not be cost-effective
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/transactions/205 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live and returns a valid x402 402 challenge, but there is no documentation, no OpenAPI schema, no request/response examples, and no explanation of what the /api/v1/transactions/205 endpoint actually does. The docs pages are empty beyond a wallet-connect prompt. This is effectively a stub listing.
Warnings
- —No documentation available — all doc pages render only 'Connect wallet' with no content
- —No OpenAPI or request/response schema provided for any endpoint
- —The purpose and output of /api/v1/transactions/205 ('Premium API Access') is completely undocumented
- —The platform lists many API categories (AI, finance, data, infrastructure) but provides zero detail on any of them
Citations
- —The endpoint returns a 402 challenge requesting up to 20,000 base units of USDC ($0.02) on Base networkhttps://lowpaymentfee.com/api/v1/transactions/205
- —The platform lists APIs across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categories, all at $0.02/requesthttps://lowpaymentfee.com
- —No API keys, no rate limits, instant access advertisedhttps://lowpaymentfee.com
- —USDC asset contract 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base networkhttps://lowpaymentfee.com/api/v1/transactions/205