Pay-per-call API platform on Base network via x402 — $0.02/request in USDC.
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/Web3 data, and utility services. Every endpoint is priced at $0.02 per request, payable in USDC on the Base network with no API keys, no rate limits, and no upfront commitments. The x402 payment protocol handles authentication and billing inline: callers attach an X-PAYMENT header with a signed USDC payment, and the server fulfills the request upon verification.
The specific endpoint probed (/api/v1/transactions/252) is listed as "Premium API Access" and returned a valid 402 challenge with a maxAmountRequired of 20,000 base units of USDC (0x8335…2913 on Base), which equals $0.02 given USDC's 6 decimals. The challenge specifies the "exact" payment scheme, a 300-second timeout, and expects HTTP POST requests. The platform advertises categories including sentiment analysis, text summarization, classification, embeddings, price feeds, exchange rates, token quotes, gas estimates, geocoding, validation, conversion, and data export — all at the same $0.02 price point.
Documentation is extremely thin: the /docs, /api, /pricing, and /README pages all render only a "Connect wallet" prompt with no further technical detail. There is no OpenAPI spec, no request/response schema documentation, and no usage examples available from the crawl. The endpoint is live and the x402 challenge is well-formed, but without documentation it is unclear what request body the /api/v1/transactions/252 endpoint expects or what response it returns.
Capabilities
Use cases
- —Calling AI inference endpoints (sentiment, summarization, classification, embeddings) without API key management
- —Fetching real-time crypto prices, gas estimates, and exchange rates with per-request USDC payments
- —Using utility services like geocoding, validation, and data conversion on a pay-as-you-go basis
- —Agent-driven workflows that need programmatic, keyless API access settled on-chain
Fit
Best for
- —Developers wanting zero-commitment, pay-per-use API access
- —AI agents that can settle x402 payments autonomously on Base
- —Projects needing low-cost micropayment-gated endpoints without subscription overhead
Not for
- —Users who need detailed API documentation or OpenAPI specs before integrating
- —High-volume use cases where per-request crypto settlement overhead is impractical
- —Developers who cannot transact in USDC on the Base network
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/transactions/252 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <signed-x402-payment-header>" \
-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, there is no OpenAPI spec, no request/response schema, and all documentation pages render only 'Connect wallet' with no technical content. The specific purpose of /api/v1/transactions/252 is undocumented beyond the generic label 'Premium API Access'.
Warnings
- —No API documentation available — all doc pages show only 'Connect wallet'
- —No OpenAPI or JSON schema for request/response bodies
- —The purpose and expected input of /api/v1/transactions/252 is unclear; 'Premium API Access' is a generic label
- —The broad catalog of endpoints (AI, finance, utilities) is advertised but none have documented schemas
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 with 300-second timeouthttps://lowpaymentfee.com/api/v1/transactions/252
- —Platform offers endpoints across Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com