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 collection of endpoints spanning data analytics, AI/ML inference, finance/Web3 data, and general utility services. All endpoints are paid per-request using USDC on the Base network via the x402 protocol — no API keys, no rate limits, and no upfront commitments.
The specific endpoint at `/api/v1/invoices/14` is listed as "Premium API Access" and accepts POST requests. The x402 challenge indicates a maximum cost of 20,000 base units of USDC (0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Base, which equals $0.02 USD (USDC uses 6 decimals). Payment is sent to address 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3 with a 300-second timeout.
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/request price point. However, documentation pages (docs, pricing, README) returned only a "Connect wallet" prompt with no substantive content, so the actual behavior and response schemas of these endpoints remain undocumented and unverified.
Capabilities
Use cases
- —Accessing AI inference (sentiment, summarization, classification, embeddings) without API key management
- —Fetching real-time crypto quotes, gas estimates, and exchange rates on a per-call basis
- —Running geocoding or data validation tasks with instant pay-as-you-go pricing
- —Exporting data or generating analytics reports via micropayment-gated endpoints
Fit
Best for
- —Developers wanting zero-signup, pay-per-use API access
- —Agents or bots that can settle payments in USDC on Base via x402
- —Projects needing low-cost micropayment-gated utility and AI endpoints
Not for
- —Users who need detailed API documentation or guaranteed SLAs before integrating
- —Applications requiring high-throughput bulk access at volume-discounted rates
- —Users without USDC on the Base network
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/invoices/14 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-header>"Endpoint
Quality
The x402 challenge is live and pricing is clear ($0.02 USDC on Base), but there is no OpenAPI schema, no documented request/response formats, and all documentation pages return only a wallet-connect prompt. The actual functionality behind 'Premium API Access' at /api/v1/invoices/14 is unspecified.
Warnings
- —No API documentation available — docs, pricing, and README pages all return only 'Connect wallet' with no content.
- —No request or response schema provided for any endpoint; actual behavior is unknown.
- —The endpoint path '/api/v1/invoices/14' with description 'Premium API Access' is vague and does not clarify what data or service is returned.
- —The platform lists many endpoints on its landing page but none have been independently verified for functionality.
Citations
- —The x402 challenge returns 402 with maxAmountRequired of 20000 base units of USDC on Base networkhttps://lowpaymentfee.com/api/v1/invoices/14
- —All endpoints are priced at $0.02 per request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —The platform offers endpoints across Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com
- —USDC contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/invoices/14