x402-gated API collection on Base — pay $0.02 per request in USDC, no API keys required.
What it does
lowpaymentfee.com hosts a suite of x402-protocol pay-per-call APIs spanning data analytics, AI/ML inference, finance/Web3 data, and utility services. Every endpoint is gated by the x402 payment challenge: callers attach a USDC payment on the Base network in the X-PAYMENT header and receive the response immediately — no API keys, no accounts, no rate limits.
The specific endpoint at `/api/v1/collections/29` is listed as "Premium API Access" and accepts POST requests. The x402 challenge advertises a maxAmountRequired of 20,000 base units of USDC (contract 0x8335…2913 on Base), which equals $0.02 per request (USDC uses 6 decimals). The broader site advertises the same $0.02/request price across all its endpoints.
The site organizes its APIs into four categories: Data & Analytics (metrics, reports, 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, /pricing, /api, and /README pages all render only a "Connect wallet" prompt with no further content. There is no OpenAPI spec, no request/response schema documentation, and no usage examples available from the crawled material.
Capabilities
Use cases
- —Agents that need on-demand AI inference (sentiment, summarization, classification, embeddings) without managing API keys
- —Fetching real-time crypto token quotes or gas estimates with per-call USDC micropayments
- —Geocoding or data validation as a utility service paid per request on Base
Fit
Best for
- —AI agents with Base USDC wallets needing frictionless API access
- —Developers prototyping with pay-per-use endpoints and no signup
- —Web3-native applications that prefer on-chain payment over subscription billing
Not for
- —High-volume production workloads where $0.02/request adds up quickly without bulk discounts
- —Users who need detailed API documentation, SLAs, or guaranteed uptime
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/collections/29 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>" \
-d '{}'Endpoint
Quality
The endpoint is live (402 challenge confirmed) and pricing is clear ($0.02 USDC on Base). However, there is no OpenAPI spec, no request/response schema, no documentation beyond endpoint names, and no examples. The /docs and other pages are empty. It is impossible to determine what this specific 'collections/29' endpoint actually returns or what input it expects.
Warnings
- —No API documentation available — /docs, /api, /pricing, and /README pages all render only 'Connect wallet' with no content
- —No OpenAPI or JSON schema describing request or response formats for any endpoint
- —The specific purpose of /api/v1/collections/29 ('Premium API Access') is unclear — it may be a bundle or a specific resource but no details are provided
- —Cannot verify what data or service is actually delivered after payment
Citations
- —The endpoint returns a 402 x402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/collections/29
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/collections/29
- —Site advertises $0.02/request pricing with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —Available API categories include Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructurehttps://lowpaymentfee.com