Pay-per-call API platform on Base via x402 — $0.02/request, no API keys required.
What it does
lowpaymentfee.com is an x402-enabled API platform that offers a broad catalog of endpoints spanning data analytics, AI/ML inference, finance/Web3 data, and utility services. Every endpoint costs $0.02 per request, paid in USDC on the Base network via the x402 payment protocol. There are no API keys, no rate limits, and no subscription commitments — callers simply attach an X-PAYMENT header with a valid x402 payment proof to access any endpoint.
The specific endpoint at `/api/v1/charges/321` is listed as "Premium API Access" and returns a 402 challenge requesting up to 20,000 base units of USDC (0x8335…2913 on Base), which equals $0.02 given USDC's 6 decimals. The challenge specifies the `exact` payment scheme with a 300-second timeout. The endpoint accepts POST requests and returns `application/json`.
The broader 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 pages exist at /docs, /pricing, and /api but currently render only a "Connect wallet" prompt with no substantive content, so the actual request/response schemas for individual endpoints are unknown.
Capabilities
Use cases
- —Agent-driven data retrieval without managing API keys or subscriptions
- —On-demand AI inference (sentiment, summarization, classification, embeddings) paid per call
- —Fetching real-time crypto prices, gas estimates, and exchange rates via micropayments
- —Geocoding and data conversion utilities with zero setup
Fit
Best for
- —AI agents that need frictionless, keyless API access via crypto micropayments
- —Developers prototyping with many different API categories at low per-call cost
- —Web3-native applications that prefer on-chain payment settlement over traditional billing
Not for
- —High-volume production workloads where $0.02/request adds up significantly
- —Users who need detailed API documentation, SLAs, or guaranteed uptime
- —Teams without access to USDC on Base network for payment
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/charges/321 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-proof>"Endpoint
Quality
The endpoint is live and returns a valid x402 402 challenge, confirming pricing and payment details. However, there is no OpenAPI schema, no documentation beyond a wallet-connect prompt, no request/response examples, and the specific purpose of the /api/v1/charges/321 endpoint (beyond 'Premium API Access') is unclear. The platform lists many endpoints but provides no substantive docs for any of them.
Warnings
- —Documentation pages (/docs, /pricing, /api, /README) all render only 'Connect wallet' with no usable content
- —No OpenAPI or schema available for any endpoint — request and response formats are unknown
- —The specific function of /api/v1/charges/321 ('Premium API Access') is not explained anywhere
- —No information on uptime, SLAs, rate limits, or data sources
Citations
- —The platform offers endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categories, all at $0.02/requesthttps://lowpaymentfee.com
- —Pricing is $0.02 per request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —The x402 challenge for /api/v1/charges/321 requests maxAmountRequired of 20000 base units of USDC (asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Basehttps://lowpaymentfee.com/api/v1/charges/321