Pay-per-call API platform on Base (USDC) covering data, AI, finance, and utility endpoints at $0.02/request.
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/crypto market 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 subscriptions required.
The specific endpoint at `/api/v1/invoices/34` is listed as "Premium API Access" and accepts POST requests. The x402 challenge indicates a maximum cost of 20,000 base units of USDC (0x8335…2913 on Base), which equals $0.02 per call (USDC uses 6 decimals). The broader platform advertises the same $0.02 flat rate across all its endpoints, which include sentiment analysis, text summarization, classification, embeddings, price feeds, exchange rates, gas estimates, geocoding, validation, conversion, and data export.
Documentation is extremely sparse — the /docs, /pricing, /api, 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 usage examples available from the crawled material. The endpoint is confirmed live (returns a valid 402 challenge), but without documentation it is unclear what request body `/api/v1/invoices/34` expects or what response payload it returns.
Capabilities
Use cases
- —Agents that need on-demand AI inference (sentiment, summarization, classification) without managing API keys
- —Fetching real-time crypto token quotes and gas estimates via micropayment
- —Geocoding or data validation as a utility service with no subscription commitment
- —Exporting analytics data or generating reports on a per-request basis
Fit
Best for
- —AI agents needing keyless, pay-per-use access to diverse API endpoints
- —Developers who want to avoid subscription overhead for low-volume API usage
- —Crypto-native applications that can settle payments in USDC on Base
Not for
- —High-volume production workloads where subscription pricing would be cheaper
- —Users who need detailed API documentation and guaranteed SLAs before integrating
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/invoices/34 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>" \
-d '{}'Endpoint
Quality
The endpoint is live and returns a valid x402 challenge with clear pricing, but documentation is effectively nonexistent — all doc pages show only 'Connect wallet'. There is no OpenAPI spec, no request/response schema, and no examples. The specific purpose of /api/v1/invoices/34 is unclear beyond the generic 'Premium API Access' label.
Warnings
- —Documentation pages (/docs, /pricing, /api, /README) are all empty, rendering only a 'Connect wallet' prompt
- —No OpenAPI or schema documentation available for any endpoint
- —The purpose and expected request body for /api/v1/invoices/34 specifically is undocumented
- —The broad catalog of endpoints (AI, finance, data, utils) is advertised on the landing page but none have verifiable documentation
Citations
- —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 x402 challenge for /api/v1/invoices/34 specifies maxAmountRequired of 20000 base units of USDC (asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Basehttps://lowpaymentfee.com/api/v1/invoices/34
- —Available endpoint categories include Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructurehttps://lowpaymentfee.com
- —Documentation pages render only 'Connect wallet' with no additional contenthttps://lowpaymentfee.com/docs