Pay-per-call API platform on Base (USDC) offering data, AI, finance, and utility endpoints at $0.02/request.
What it does
lowpaymentfee.com is an x402-enabled API platform that provides a broad catalog of pay-per-request endpoints settled in USDC on the Base network. The specific endpoint at `/api/v1/invoices/49` is labeled "Premium API Access" and charges up to $0.02 per call (20,000 base units of USDC with 6 decimals). No API keys or accounts are required — callers authenticate and pay via the x402 protocol's X-PAYMENT header.
The platform advertises four endpoint 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 listed endpoints share the same $0.02/request pricing with no rate limits or minimum commitments.
Documentation is extremely sparse — the docs, API, pricing, and README pages all render only a "Connect wallet" prompt with no further content. There is no OpenAPI spec, no request/response schema documentation, and no usage examples available from the crawled material. The specific functionality behind the `/api/v1/invoices/49` endpoint is unclear beyond its "Premium API Access" label; it may be an invoice retrieval or creation endpoint, but this is speculative.
Capabilities
Use cases
- —Accessing AI inference endpoints (sentiment, summarization, classification, embeddings) without API key signup
- —Fetching real-time financial data like token quotes, gas estimates, and exchange rates on a per-call basis
- —Running utility operations like geocoding, validation, and data conversion with instant crypto payment
- —Integrating pay-as-you-go data analytics into agent workflows
Fit
Best for
- —Developers wanting instant API access without registration or API keys
- —AI agents that can settle payments via x402 on Base
- —Low-volume or bursty workloads where per-request pricing is more economical than subscriptions
Not for
- —High-volume production workloads needing SLAs and guaranteed uptime documentation
- —Users without USDC on the Base network or x402-compatible payment infrastructure
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/invoices/49 \
-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/request in USDC on Base). However, there is no OpenAPI spec, no request/response schema, no documentation beyond a wallet-connect prompt, and the specific purpose of the /api/v1/invoices/49 endpoint is ambiguous. Effectively a stub listing.
Warnings
- —Documentation pages (docs, API, pricing, README) all return only a 'Connect wallet' prompt with no actual content
- —No OpenAPI or schema documentation available for any endpoint
- —The specific functionality of /api/v1/invoices/49 ('Premium API Access') is unclear — it may differ from the other advertised endpoints
- —Cannot verify that the advertised AI, finance, data, and utility endpoints actually return meaningful data
Citations
- —The platform charges $0.02 per request with no API keys, no rate limits, and instant access on the Base networkhttps://lowpaymentfee.com
- —The x402 challenge for /api/v1/invoices/49 specifies maxAmountRequired of 20000 base units of USDC (USD Coin) on Basehttps://lowpaymentfee.com/api/v1/invoices/49
- —The platform offers endpoints in four categories: Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructurehttps://lowpaymentfee.com
- —Payment is sent to address 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3 using USDC contract 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/invoices/49