Pay-per-call API platform on Base (USDC) via x402 — $0.02/request, no API keys required.
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 costs $0.02 per request, paid in USDC on the Base network via the x402 payment protocol. There are no API keys, no rate limits, and no upfront commitments — callers simply attach an X-PAYMENT header with a valid x402 payment proof to access any endpoint.
The specific endpoint at `/api/v1/transactions/231` is listed as "Premium API Access" and returns JSON. The x402 challenge confirms it accepts POST requests, settles on Base using USDC (contract 0x8335…2913), and requires a maximum of 20,000 base units (i.e., $0.02 given USDC's 6 decimals). The broader platform advertises categories including metrics, reports, data export, insights, sentiment analysis, text summarization, classification, embeddings, price feeds, exchange rates, token quotes, gas estimates, geocoding, validation, conversion, and generation.
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 crawl. The endpoint is confirmed live (402 challenge captured), but the actual behavior and response format of `/api/v1/transactions/231` specifically is unknown beyond the description "Premium API Access" and mimeType "application/json".
Capabilities
Use cases
- —Accessing analytics metrics or reports without signing up for an API key
- —Running AI inference tasks (sentiment, summarization, classification, embeddings) on a per-call payment basis
- —Fetching real-time crypto token quotes, gas estimates, or exchange rates
- —Geocoding or data conversion via utility endpoints
Fit
Best for
- —Agents or bots that need instant, keyless API access paid per call
- —Developers prototyping with low-commitment, pay-as-you-go endpoints
- —Web3-native applications that already hold USDC on Base
Not for
- —Users who need detailed API documentation or guaranteed SLAs before integrating
- —High-volume production workloads where $0.02/request adds up significantly
- —Users without a Base-compatible wallet or USDC holdings
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/transactions/231 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-proof>"Endpoint
Quality
The endpoint is confirmed live via a valid 402 x402 challenge, and pricing is clear ($0.02/request in USDC on Base). However, there is no OpenAPI spec, no request/response schema, no documentation beyond a wallet-connect prompt, and no examples. The specific purpose of /api/v1/transactions/231 is opaque — 'Premium API Access' is not descriptive. This is effectively a stub listing.
Warnings
- —No OpenAPI or schema documentation available — all /docs, /pricing, /api, and /README pages return only 'Connect wallet' with no content
- —The specific purpose and expected input/output of /api/v1/transactions/231 is undocumented; 'Premium API Access' is vague
- —The broader platform advertises many endpoint categories (AI, finance, analytics, utilities) but none have documented request/response schemas
- —Cannot verify that the advertised endpoints actually function as described without paying
Citations
- —The endpoint returns a 402 x402 challenge with maxAmountRequired of 20000 base units in USDC on Basehttps://lowpaymentfee.com/api/v1/transactions/231
- —All endpoints cost $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
- —Documentation pages (/docs, /pricing, /api, /README) render only a 'Connect wallet' prompthttps://lowpaymentfee.com/docs