Pay-per-request API platform on Base via x402 — data, AI, finance, and utility endpoints at $0.02/call.
What it does
lowpaymentfee.com is an x402-enabled API platform that offers a broad catalog of pay-per-request 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 priced at $0.02 per request, paid in USDC on the Base network via the x402 protocol.
The specific endpoint at `/api/v1/invoices/22` is listed as "Premium API Access" and carries a maximum charge of 20,000 base units of USDC (0.02 USDC = $0.02), consistent with the site-wide pricing. The platform advertises no API keys, no rate limits, no minimums, and instant access — payment is handled entirely through the x402 payment header.
Documentation is extremely sparse. The docs, API, pricing, and README pages all render only a "Connect wallet" prompt with no substantive content. There is no OpenAPI schema, no request/response examples, and no detailed documentation for any endpoint. The exact functionality behind `/api/v1/invoices/22` (as opposed to the other listed endpoints) is unclear from available materials. Agents should be aware that without schemas or examples, integration requires experimentation or additional out-of-band information.
Capabilities
Use cases
- —Accessing AI inference endpoints (sentiment, summarization, classification, embeddings) without API key management
- —Fetching real-time financial data such as token quotes, exchange rates, and gas estimates
- —Running utility operations like geocoding, validation, and data conversion on a per-request payment basis
- —Exporting data or generating analytics reports with no subscription commitment
Fit
Best for
- —Agents or developers who want zero-signup, pay-as-you-go API access
- —Crypto-native applications that can settle payments in USDC on Base
- —Low-volume or bursty workloads where per-request pricing is more economical than subscriptions
Not for
- —High-volume production workloads that need guaranteed SLAs and detailed documentation
- —Developers who need comprehensive OpenAPI schemas and request/response examples before integration
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/invoices/22 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live (402 challenge captured) and pricing is clear ($0.02 USDC on Base), but there is no OpenAPI schema, no request/response examples, and all documentation pages return only a wallet-connect prompt. The specific purpose of /api/v1/invoices/22 versus the other listed endpoints is unclear.
Warnings
- —No OpenAPI schema or AI plugin manifest available
- —All documentation pages (docs, API, pricing, README) render only 'Connect wallet' with no substantive content
- —The exact functionality of /api/v1/invoices/22 ('Premium API Access') is not documented — it does not appear in the site's listed endpoint catalog
- —No request or response examples are available for any endpoint
Citations
- —All endpoints are priced at $0.02 per request with no API keys, no rate limits, and instant access on the Base networkhttps://lowpaymentfee.com
- —The platform offers endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com
- —The x402 challenge for /api/v1/invoices/22 shows maxAmountRequired of 20000 base units of USDC (USD Coin) on Basehttps://lowpaymentfee.com/api/v1/invoices/22
- —Documentation pages render only a 'Connect wallet' prompt with no substantive contenthttps://lowpaymentfee.com/docs