Pay-per-call API key generation on Base via x402, settled in USDC at $0.02/request.
What it does
lowpaymentfee.com is an x402-enabled API platform that offers a variety of endpoints across data analytics, AI/ML inference, finance/Web3, and infrastructure utilities — all payable per-request with USDC on the Base network. The specific endpoint at `/api/v1/apikeys/12` is labeled "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 exact-payment scheme: callers attach an `X-PAYMENT` header with a signed payment proof, and the server fulfills the request upon verification.
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 — all at the same $0.02/request price point. The site emphasizes no API keys required (for the other endpoints), no rate limits, and instant access. However, documentation pages (`/docs`, `/pricing`, `/README`) returned only a "Connect wallet" prompt with no substantive content, so detailed request/response schemas, parameter descriptions, and example payloads are unavailable.
The endpoint is live and returns a proper 402 challenge with x402 version 1. It accepts POST requests, pays to address `0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3`, and uses USDC (contract `0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913`) on Base. The maximum timeout for payment settlement is 300 seconds.
Capabilities
Use cases
- —Purchasing premium API access tokens via a single USDC micropayment on Base
- —Accessing AI inference endpoints (sentiment, summarization, classification, embeddings) without subscription
- —Fetching real-time crypto quotes, gas estimates, and exchange rates on a pay-per-call basis
- —Running geocoding, validation, and data conversion utilities without API key management
Fit
Best for
- —Developers wanting zero-commitment, pay-as-you-go API access settled in USDC
- —AI agents that can autonomously pay for API calls via x402 protocol
- —Projects needing low-cost micropayment-gated endpoints on Base L2
Not for
- —Users who need detailed API documentation and typed schemas before integrating
- —High-volume consumers who would benefit from bulk pricing or subscription plans
- —Developers who cannot transact in USDC on the Base network
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/apikeys/12 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <signed-x402-payment-proof>"Endpoint
Quality
The endpoint is live and returns a valid x402 402 challenge, confirming pricing and payment details. However, documentation pages are empty (only 'Connect wallet'), there is no OpenAPI schema, no request/response examples, and the purpose of the specific '/api/v1/apikeys/12' endpoint beyond its label is unclear.
Warnings
- —Documentation pages (/docs, /pricing, /README) contain no substantive content — only a 'Connect wallet' prompt.
- —No OpenAPI or JSON schema available; request parameters and response format are unknown.
- —The specific behavior of the /api/v1/apikeys/12 endpoint (what it returns, what input it expects) is undocumented.
- —Many listed endpoints on the site may be demo/placeholder — no independent verification of their functionality.
Citations
- —The endpoint returns a 402 challenge with x402 version 1, accepting USDC on Base with maxAmountRequired of 20000 base units ($0.02).https://lowpaymentfee.com/api/v1/apikeys/12
- —The platform lists endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categories, all at $0.02/request.https://lowpaymentfee.com
- —The site advertises no API keys, no rate limits, instant access, and Base network settlement.https://lowpaymentfee.com
- —USDC contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 and payTo address is 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3.https://lowpaymentfee.com/api/v1/apikeys/12