Pay-per-call API access on Base via x402 — $0.02/request in USDC, no keys required.
What it does
lowpaymentfee.com is an x402-enabled API platform that offers a suite 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. The x402 protocol means there are no API keys, no sign-ups, and no rate limits — callers simply attach a payment header to each request.
The specific endpoint at `/api/v1/keys/85` is listed as "Premium API Access" and accepts POST requests. Its x402 challenge advertises a max amount of 20,000 base units of USDC (0x8335…2913 on Base), which equals $0.02 given USDC's 6 decimals. Payment is settled on-chain to the provider's wallet. The timeout window is 300 seconds.
The broader platform advertises endpoints in 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 (geocoding, validation, conversion, generation). All are priced identically at $0.02 per call. However, no OpenAPI schema, request/response examples, or detailed documentation were found for any endpoint, so the actual input parameters and response formats remain unknown.
Capabilities
Use cases
- —Agents that need on-demand AI inference (sentiment, summarization, classification, embeddings) without managing API keys
- —Fetching real-time financial data like token quotes, gas estimates, or exchange rates with per-call payment
- —Running data analytics queries or exporting data with no subscription commitment
- —Geocoding, validation, or conversion utilities paid per use via crypto
Fit
Best for
- —AI agents and bots that can attach x402 payment headers automatically
- —Developers who want zero-signup, pay-as-you-go API access
- —Low-volume or bursty workloads where subscriptions are wasteful
Not for
- —Users who need detailed API documentation or guaranteed SLAs before integrating
- —High-volume production workloads where per-call crypto settlement adds latency or cost overhead
- —Callers without a Base-network USDC wallet or x402-compatible client
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/keys/85 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-header>" \
-d '{}'Endpoint
Quality
The endpoint is live and returns a valid x402 challenge, confirming pricing and payment details. However, there is no OpenAPI schema, no request/response examples, and no documentation beyond a marketing landing page. The purpose of this specific endpoint (/api/v1/keys/85 — 'Premium API Access') is unclear and may differ from the other listed endpoints. Effectively a stub listing.
Warnings
- —No OpenAPI or schema documentation available for any endpoint
- —The specific purpose and expected input/output of /api/v1/keys/85 ('Premium API Access') is undocumented and unclear — it may be a key-generation or access-granting endpoint rather than a data API
- —No request or response examples could be found
- —The /api, /pricing, and /README pages all returned only a 'Connect wallet' prompt with no useful content
Citations
- —All endpoints cost $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/keys/85 advertises maxAmountRequired of 20000 base units of USDC (asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Basehttps://lowpaymentfee.com/api/v1/keys/85
- —The platform offers endpoints in Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com