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 collection of endpoints spanning data analytics, AI/ML inference, finance/Web3, and infrastructure utilities. All endpoints are paid per-request using USDC on the Base network via the x402 protocol — no API keys, no rate limits, and no subscriptions required.
The specific endpoint at `/api/v1/invoices/41` is listed as "Premium API Access" and charges up to 20,000 base units of USDC (i.e., $0.02) per call, consistent with the site's uniform $0.02/request pricing. The platform advertises 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 (geocoding, validation, conversion, generation).
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 schema, no request/response examples, and no detailed documentation for any endpoint. The x402 challenge is live and well-formed, confirming the endpoint accepts POST requests and settles payments to address 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3 using USDC (contract 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Base.
Capabilities
Use cases
- —Accessing AI inference (sentiment, summarization, classification, embeddings) without API key management
- —Fetching real-time finance and crypto market data on a per-request basis
- —Running geocoding or data validation calls paid directly with USDC on Base
- —Integrating pay-as-you-go analytics and data export into agent workflows
Fit
Best for
- —Developers wanting zero-signup, pay-per-call API access
- —AI agents that can settle x402 payments autonomously on Base
- —Projects needing low-cost ($0.02) utility and AI endpoints without subscriptions
Not for
- —Users who need detailed API documentation or OpenAPI schemas before integrating
- —High-volume production workloads requiring SLAs, rate-limit guarantees, or support contracts
- —Developers without USDC on Base or unfamiliar with x402 payment flows
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/invoices/41 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The x402 challenge is live and pricing is clear ($0.02/request in USDC on Base). However, there is no OpenAPI schema, no request/response examples, and all documentation pages render only a wallet-connect prompt. The purpose of the specific /invoices/41 endpoint is unclear beyond its generic 'Premium API Access' label. Effectively a stub listing.
Warnings
- —No API documentation available — docs, pricing, API, and README pages all show only 'Connect wallet'
- —No OpenAPI or JSON schema provided for any endpoint
- —The specific purpose and expected input/output of /api/v1/invoices/41 is undocumented
- —The broad catalog of advertised endpoints (AI, finance, data, utils) cannot be verified for actual functionality
Citations
- —Uniform 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 (6 decimals = $0.02) on Basehttps://lowpaymentfee.com/api/v1/invoices/41
- —USDC asset contract is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/invoices/41
- —Platform advertises endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com