Pay-per-call API platform on Base network via x402 — $0.02/request in USDC.
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 with no API keys, no rate limits, and no upfront commitments. The x402 payment challenge is returned as a standard 402 response, and callers settle directly on-chain.
The specific endpoint at `/api/v1/transactions/221` is listed as "Premium API Access" and returns a 402 challenge requesting up to 20,000 base units of USDC (0x8335…2913 on Base). Since USDC uses 6 decimals, this equals $0.02 per call — consistent with the site's advertised flat pricing. The endpoint accepts POST requests and returns `application/json`.
The broader platform advertises endpoints for sentiment analysis, text summarization, classification, embeddings, price feeds, exchange rates, token quotes, gas estimates, geocoding, validation, conversion, and data generation. However, documentation pages (/docs, /pricing, /api, /README) all returned only a "Connect wallet" prompt with no substantive content, so the actual behavior and response schemas of these endpoints are undocumented in the crawled material.
Capabilities
Use cases
- —Agents that need on-demand AI inference (sentiment, summarization, classification, embeddings) without API key management
- —Fetching real-time crypto token quotes, gas estimates, or exchange rates with per-call payment
- —Geocoding or data validation as a utility microservice settled in USDC on Base
Fit
Best for
- —AI agents with Base USDC wallets needing frictionless API access
- —Developers who want pay-per-use without subscriptions or API keys
- —Web3-native applications that prefer on-chain settlement for API calls
Not for
- —High-volume batch workloads where $0.02/request adds up quickly
- —Users without a Base-network USDC wallet or x402-compatible client
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/transactions/221 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live and returns a valid x402 challenge with clear pricing. However, documentation pages are empty (all show only 'Connect wallet'), there is no OpenAPI spec, no request/response schema, and the specific purpose of /api/v1/transactions/221 ('Premium API Access') is unexplained. The platform lists many endpoints but provides no details on inputs, outputs, or actual functionality.
Warnings
- —All documentation pages (/docs, /pricing, /api, /README) returned no useful content — only 'Connect wallet' prompts
- —No OpenAPI or schema available; request and response formats for this endpoint are unknown
- —The specific endpoint /api/v1/transactions/221 is labeled 'Premium API Access' but its actual function is undocumented
- —The broader catalog lists many endpoint categories (AI, finance, utils) but none have documented schemas or example responses
Citations
- —The endpoint returns a 402 challenge requesting up to 20,000 base units of USDC on Base networkhttps://lowpaymentfee.com/api/v1/transactions/221
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/transactions/221
- —All endpoints cost $0.02 per request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —Platform offers endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com