Pay-per-call API platform on Base offering data, AI, finance, and utility endpoints at $0.02 each via x402.
What it does
lowpaymentfee.com is an x402-enabled API marketplace that exposes a broad set of endpoints across four categories: Data & Analytics (metrics, reports, data export, insights), AI & Machine Learning (sentiment analysis, text summarization, classification, embeddings), Finance & Web3 (price feeds, exchange rates, token quotes, gas estimates), and Infrastructure utilities (geocoding, validation, conversion, generation). All endpoints are priced at $0.02 per request, paid in USDC on the Base network with no API keys, no rate limits, and no minimum commitments.
The specific endpoint at `/api/v1/invoices/26` is listed as "Premium API Access" and returns a valid x402 challenge with a maxAmountRequired of 20,000 base units of USDC (0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913), which equals $0.02 given USDC's 6 decimals. Payment is made via the "exact" scheme on the Base network to address 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3, with a 300-second timeout. The endpoint accepts POST requests and returns application/json.
Documentation beyond the landing page is extremely sparse — the /docs, /api, /pricing, 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 example payloads available. The exact functionality behind the `/api/v1/invoices/26` path is unclear; it may be an invoice lookup or a generic premium access gate. Without documentation, callers will need to experiment to determine the expected request body and response format.
Capabilities
Use cases
- —Accessing AI inference endpoints (sentiment, summarization, classification, embeddings) without API key management
- —Fetching real-time finance data such as token quotes, gas estimates, and exchange rates on a per-call basis
- —Running data analytics queries and exporting data with per-request micropayments
- —Using utility services like geocoding and validation without subscription commitments
Fit
Best for
- —Agents or developers who want zero-signup, pay-as-you-go API access
- —Use cases requiring low-cost micropayment-gated endpoints on Base
- —Projects already holding USDC on Base that need quick access to diverse utility APIs
Not for
- —Production workloads requiring documented request/response schemas and SLAs
- —Users without USDC on the Base network or unfamiliar with x402 payment flows
- —High-volume use cases where $0.02 per request adds up significantly
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/invoices/26 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>" \
-d '{}'Endpoint
Quality
The x402 challenge is live and well-formed, confirming the endpoint works and pricing is clear ($0.02 USDC on Base). However, documentation is essentially nonexistent beyond the landing page listing; no OpenAPI spec, no request/response schemas, no examples, and the specific purpose of /api/v1/invoices/26 is ambiguous. This is effectively a stub listing.
Warnings
- —No API documentation available — /docs, /api, /pricing, and /README all render only a wallet-connect prompt
- —No OpenAPI or schema definition found for any endpoint
- —The purpose and expected request body for /api/v1/invoices/26 specifically is unclear — it may differ from the other listed endpoints
- —No example request or response payloads are available anywhere in the crawled content
Citations
- —All endpoints priced at $0.02 per request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —x402 challenge returns maxAmountRequired of 20000 base units of USDC (asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Base networkhttps://lowpaymentfee.com/api/v1/invoices/26
- —Available API categories include Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructurehttps://lowpaymentfee.com
- —Documentation pages (/docs, /api, /pricing, /README) render only a Connect wallet prompthttps://lowpaymentfee.com/docs