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 `/api/v1/keys/40` is listed as "Premium API Access" and costs up to $0.02 per call (20,000 base units of USDC with 6 decimals). Payment is handled via the x402 protocol — no API keys, accounts, or subscriptions are required; callers attach an X-PAYMENT header with each request.
The wider 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.
Important caveat: the specific functionality behind `/api/v1/keys/40` is not documented beyond the label "Premium API Access." There is no OpenAPI spec, no request/response schema, and the crawled docs pages (pricing, README, API) returned only a wallet-connect prompt with no additional detail. Treat this listing as a stub until richer documentation becomes available.
Capabilities
Use cases
- —Agent-driven data retrieval without API key management
- —On-demand AI inference (sentiment, summarization, classification, embeddings) paid per call
- —Fetching real-time crypto gas estimates or token quotes with micropayments
- —Geocoding or data conversion as a utility microservice
Fit
Best for
- —AI agents that need frictionless, keyless API access
- —Developers wanting pay-as-you-go endpoints without subscriptions
- —Crypto-native applications already on Base that can settle in USDC
Not for
- —High-volume batch processing where per-call fees add up quickly
- —Users who need detailed SLAs, uptime guarantees, or enterprise support
- —Applications requiring well-documented request/response schemas before integration
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/keys/40 \
-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 USDC on Base), but there is no OpenAPI spec, no request/response schema, no documentation of what /api/v1/keys/40 actually returns, and the crawled doc pages were empty. This is effectively a stub listing.
Warnings
- —No OpenAPI or schema available — request and response formats are unknown
- —The specific endpoint /api/v1/keys/40 ('Premium API Access') has no documentation explaining its functionality
- —Crawled /pricing, /README, and /api pages returned only a wallet-connect prompt with no content
- —No rate-limit or uptime guarantees documented
Citations
- —The endpoint returns a 402 x402 challenge with maxAmountRequired 20000 in USDC on Basehttps://lowpaymentfee.com/api/v1/keys/40
- —All listed endpoints cost $0.02 per request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —Platform offers Data & Analytics, AI & ML, Finance & Web3, and Infrastructure endpoint categorieshttps://lowpaymentfee.com
- —USDC asset address 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base networkhttps://lowpaymentfee.com/api/v1/keys/40