Pay-per-call API platform on Base network via x402 — $0.02/request in USDC.
What it does
lowpaymentfee.com is an x402-enabled API platform that offers a variety of endpoints across data analytics, AI/ML inference, finance/Web3, and infrastructure utilities. All endpoints are paid per-request using USDC on the Base network at a flat rate of $0.02 per call, with no API keys, no rate limits, and no commitments required.
The specific endpoint at `/api/v1/invoices/16` is listed as "Premium API Access" and returns an x402 challenge requesting payment of 20,000 base units of USDC (0x8335…2913 on Base), which equals $0.02 given USDC's 6 decimals. Payment is made via the x402 exact scheme to the payTo address. The endpoint accepts POST requests and returns application/json.
The broader platform advertises endpoints for sentiment analysis, text summarization, classification, embeddings, price feeds, exchange rates, token quotes, gas estimates, geocoding, validation, conversion, and data generation — all at the same $0.02 price point. However, documentation pages (docs, pricing, API reference) appear to be behind a wallet-connect gate and provide no substantive content in the crawl. No OpenAPI schema, request/response examples, or detailed endpoint documentation were found, so the actual behavior and output of this specific invoices endpoint is unclear.
Capabilities
Use cases
- —Accessing premium API data with per-request USDC micropayments on Base
- —Agent-driven workflows that need keyless, pay-as-you-go API access
- —Programmatic invoice or data retrieval without subscription commitments
Fit
Best for
- —Developers wanting frictionless pay-per-use API access without API keys
- —AI agents that can settle x402 payments autonomously on Base
- —Users who prefer crypto micropayments over traditional subscription billing
Not for
- —Users who need detailed API documentation or OpenAPI specs before integrating
- —High-volume consumers who would benefit from bulk pricing or subscriptions
- —Developers who cannot transact in USDC on the Base network
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/invoices/16 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live and returns a valid x402 challenge, but there is no OpenAPI schema, no request/response examples, and all documentation pages are gated behind wallet-connect with no content. The purpose of the specific /invoices/16 endpoint is unclear beyond its generic 'Premium API Access' label.
Warnings
- —No OpenAPI or detailed endpoint documentation available — all doc pages return only 'Connect wallet'
- —The specific purpose and expected input/output of /api/v1/invoices/16 is undocumented
- —No request body schema or response schema could be determined from available material
- —Platform appears to be a demo or early-stage project with many advertised endpoints but no verifiable documentation
Citations
- —Flat pricing of $0.02 per request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —x402 challenge returns maxAmountRequired of 20000 base units of USDC (0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Basehttps://lowpaymentfee.com/api/v1/invoices/16
- —Platform offers endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com