Pay-per-call API key generation on Base via x402 — $0.02 per request in USDC.
What it does
lowpaymentfee.com is an x402-enabled API marketplace that offers a variety of endpoints across data & analytics, AI & machine learning, finance & Web3, and infrastructure utilities. Each endpoint costs $0.02 per request, paid in USDC on the Base network with no API keys, rate limits, or commitments required.
The specific endpoint at `/api/v1/apikeys/44` is listed as "Premium API Access." Based on the x402 challenge, it accepts POST requests and charges up to 20,000 base units of USDC (0x8335…) on Base, which equals $0.02 (USDC uses 6 decimals). Payment is settled on-chain to the specified wallet address with a 300-second timeout window.
The broader platform advertises additional endpoints including sentiment analysis, text summarization, classification, embeddings, price feeds, exchange rates, token quotes, gas estimates, geocoding, validation, conversion, and generation — all at the same $0.02 per-call price point. Documentation pages exist but appear to require wallet connection to view, so detailed request/response schemas for individual endpoints are not available from the crawl.
Capabilities
Use cases
- —Agents purchasing one-off API access without needing pre-provisioned keys
- —Pay-per-call AI inference (sentiment, summarization, classification, embeddings)
- —On-demand financial data retrieval (prices, exchange rates, gas estimates)
- —Utility operations like geocoding, validation, and data conversion
Fit
Best for
- —AI agents needing frictionless, keyless API access via x402
- —Developers who want pay-as-you-go pricing without subscriptions
- —Web3-native applications that can settle payments in USDC on Base
Not for
- —High-volume batch processing where per-call pricing becomes expensive
- —Users without a Base-compatible wallet or USDC holdings
- —Applications requiring detailed SLAs or guaranteed uptime
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/apikeys/44 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The x402 challenge is live and confirms pricing and payment details, but documentation pages all resolve to a wallet-connect prompt with no actual content. No OpenAPI schema, no request/response examples, and no detailed docs are available. The purpose of the specific /api/v1/apikeys/44 endpoint is unclear beyond the generic 'Premium API Access' label.
Warnings
- —Documentation pages (/docs, /api, /pricing, /README) all return only a 'Connect wallet' prompt with no visible content — detailed API docs are inaccessible.
- —No OpenAPI or schema information is available; request and response formats for this endpoint are unknown.
- —The specific function of /api/v1/apikeys/44 ('Premium API Access') is not clearly documented — it may generate API keys or serve another purpose.
- —The broader platform lists many endpoints but none have been individually verified beyond this one.
Citations
- —The endpoint returns a 402 x402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/apikeys/44
- —All endpoints are priced at $0.02 per request with no API keys, rate limits, or commitmentshttps://lowpaymentfee.com
- —The platform offers endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com
- —USDC asset contract is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base networkhttps://lowpaymentfee.com/api/v1/apikeys/44