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/355` is listed as "Premium API Access" and returns a 402 challenge requesting up to 20,000 base units of USDC (0.02 USD) per call. The platform advertises no API keys, no rate limits, and instant access — you simply attach an x402 payment header to each request.
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 uniformly priced at $0.02 per request.
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 schema, no request/response examples, and no description of what the `/api/v1/transactions/355` endpoint actually returns. The endpoint is live and responds with a valid x402 challenge, but without documentation it is unclear what data or functionality it provides.
Capabilities
Use cases
- —Accessing premium API data without traditional API key registration
- —Making one-off paid API calls settled in USDC on Base
- —Agent-driven workflows that need keyless, per-call payment APIs
Fit
Best for
- —Developers who want to pay per request without subscriptions or API keys
- —AI agents that can attach x402 payment headers automatically
- —Users already holding USDC on the Base network
Not for
- —Users who need detailed API documentation or OpenAPI specs before integrating
- —High-volume use cases where per-request pricing may add up compared to subscription plans
- —Developers without USDC on Base network or unfamiliar with x402 protocol
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/transactions/355 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live and returns a valid x402 402 challenge, confirming it accepts USDC on Base at $0.02/request. However, there is no OpenAPI schema, no request/response examples, and all documentation pages render only 'Connect wallet' with no technical content. The purpose of the specific /transactions/355 endpoint is undocumented.
Warnings
- —No OpenAPI or schema documentation available — endpoint behavior is unknown beyond the 402 challenge
- —All doc/pricing/API/README pages return only a 'Connect wallet' prompt with no usable content
- —The specific endpoint /api/v1/transactions/355 has no description of what data it returns or what input it expects
- —Platform lists many endpoint categories (AI, finance, analytics, infrastructure) but none have documented schemas
Citations
- —The endpoint returns a 402 challenge requesting up to 20,000 base units of USDC (asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Base networkhttps://lowpaymentfee.com/api/v1/transactions/355
- —Platform advertises $0.02/request pricing with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —Platform offers endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com
- —Docs, API, pricing, and README pages all render only a 'Connect wallet' prompthttps://lowpaymentfee.com/docs