Pay-per-call API platform on Base via x402 — 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 pay-per-request 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 via the x402 protocol.
The specific endpoint at `/api/v1/transactions/21` is listed as "Premium API Access" and its x402 challenge advertises a maxAmountRequired of 20000 base units of USDC (0x8335…2913 on Base), which equals $0.02 given USDC's 6 decimals. Payment is made per-call with no API keys, no rate limits, and no minimum commitments required. The endpoint accepts POST requests and returns application/json responses.
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 schema, no request/response examples, and no detailed documentation describing what the `/api/v1/transactions/21` endpoint actually returns or what parameters it accepts. The platform's landing page lists many endpoints but provides no specifics about their inputs or outputs beyond category labels.
Capabilities
Use cases
- —Accessing AI inference endpoints (sentiment, summarization, classification, embeddings) without API key management
- —Fetching real-time financial data like token quotes, gas estimates, and exchange rates on a per-call basis
- —Running utility operations like geocoding, validation, and data conversion with instant crypto micropayments
- —Integrating pay-as-you-go data analytics and reporting into agent workflows
Fit
Best for
- —Agents or developers who want zero-signup, pay-per-call API access
- —Use cases requiring small, infrequent API calls where subscriptions are overkill
- —Crypto-native workflows that can settle payments in USDC on Base
Not for
- —High-volume production workloads where per-call pricing at $0.02 adds up quickly
- —Users who need detailed API documentation, SDKs, or guaranteed SLAs before integrating
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/transactions/21 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live and returns a valid x402 402 challenge with clear pricing. However, there is no OpenAPI schema, no request/response examples, and all documentation pages are empty beyond a wallet-connect prompt. The purpose of the specific /api/v1/transactions/21 endpoint is unclear beyond the generic 'Premium API Access' label. Effectively a stub listing.
Warnings
- —No documentation available — /docs, /pricing, /api, and /README pages all show only 'Connect wallet' with no content
- —No OpenAPI or schema describing request parameters or response format for this endpoint
- —The specific purpose of /api/v1/transactions/21 is unclear; the landing page does not list this path among its catalog
- —No request or response examples available anywhere in the crawled material
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 this endpoint advertises maxAmountRequired of 20000 base units of USDC (asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Basehttps://lowpaymentfee.com/api/v1/transactions/21
- —The platform offers endpoints across Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com
- —Documentation pages (/docs, /pricing, /api, /README) render only a 'Connect wallet' prompthttps://lowpaymentfee.com/docs