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/keys/38` is labeled "Premium API Access" and charges up to 20,000 base units of USDC (i.e., $0.02) per call via the x402 exact payment scheme. No API keys, rate limits, or upfront commitments are required — callers simply attach an X-PAYMENT header with a valid x402 payment proof.
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. However, the probed endpoint `/api/v1/keys/38` does not clearly map to any of these named endpoints, so its exact functionality is uncertain — it may be a generic key-provisioning or access-granting endpoint.
The x402 challenge confirms the endpoint is live, accepts POST requests, settles on Base mainnet using USDC (contract 0x8335…2913), and pays to address 0x1A2B…85F3 with a 300-second timeout. No OpenAPI schema, detailed documentation, or example responses were found in the crawl.
Capabilities
Use cases
- —Agent-driven data retrieval with per-call USDC micropayments
- —On-demand AI inference (sentiment, summarization, classification, embeddings) without subscriptions
- —Fetching real-time crypto prices, gas estimates, and exchange rates via pay-per-use endpoints
- —Geocoding and data validation as utility microservices
Fit
Best for
- —AI agents that need low-friction, keyless API access with crypto micropayments
- —Developers prototyping with multiple API categories without subscription overhead
- —Web3-native applications that prefer on-chain settlement for API calls
Not for
- —High-volume production workloads where per-request pricing becomes expensive compared to bulk plans
- —Users without USDC on Base network or unfamiliar with x402 payment protocol
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/keys/38 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-proof>"Endpoint
Quality
The x402 challenge is live and confirms pricing and settlement details, but there is no OpenAPI schema, no documentation beyond a landing page listing, no example requests or responses, and the specific endpoint /api/v1/keys/38 has unclear functionality. Most detail is inferred from the homepage catalog.
Warnings
- —The endpoint /api/v1/keys/38 does not correspond to any named endpoint on the landing page; its exact functionality is unknown.
- —No OpenAPI spec, detailed docs, or example responses were found — /api, /pricing, and /README pages all returned only a 'Connect wallet' prompt.
- —No input or output schema is documented; callers must guess at the request body format.
Citations
- —All endpoints are priced at $0.02 per request with no API keys, rate limits, or commitmentshttps://lowpaymentfee.com
- —The platform offers Data & Analytics, AI & ML, Finance & Web3, and Infrastructure endpoint categorieshttps://lowpaymentfee.com
- —x402 challenge returns maxAmountRequired of 20000 base units of USDC (6 decimals = $0.02) on Base networkhttps://lowpaymentfee.com/api/v1/keys/38
- —Payment settles to 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3 using USDC contract 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/keys/38