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 costs $0.02 per request, paid in USDC on the Base network with no API keys, no rate limits, and no upfront commitments. The x402 protocol handles payment inline: callers attach a signed USDC payment in the X-PAYMENT header and receive the response immediately.
The specific endpoint at `/api/v1/transfers/173` is listed as "Premium API Access." Its x402 challenge advertises a maxAmountRequired of 20,000 base units of USDC (asset 0x8335…2913 on Base), which equals $0.02 given USDC's 6 decimals. The endpoint accepts POST requests and returns application/json. Beyond this particular path, the platform advertises endpoints for sentiment analysis, text summarization, classification, embeddings, price feeds, exchange rates, token quotes, gas estimates, geocoding, validation, conversion, and data generation — all at the same $0.02 price point.
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 example payloads available. The endpoint is live (returns a proper 402 challenge), but without documentation it is unclear what request body `/api/v1/transfers/173` expects or what it returns.
Capabilities
Use cases
- —Accessing premium API data without traditional API key registration
- —Making one-off API calls with instant USDC micropayments on Base
- —Integrating pay-as-you-go endpoints into autonomous agent workflows
- —Prototyping applications that need analytics, AI, or finance data without subscription overhead
Fit
Best for
- —Developers who want zero-signup, pay-per-use API access
- —AI agents with Base network USDC wallets needing on-demand data
- —Projects that prefer crypto micropayments over traditional billing
Not for
- —Users who need detailed API documentation or OpenAPI specs before integrating
- —High-volume consumers who would benefit from bulk/subscription pricing
- —Teams without a Base-compatible USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/transfers/173 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <signed-x402-payment-header>" \
-d '{}'Endpoint
Quality
The endpoint is live and returns a valid x402 402 challenge, confirming it accepts USDC payments on Base at $0.02. However, there is no OpenAPI spec, no request/response schema, no documentation beyond a landing page listing, and no examples. The specific purpose of /api/v1/transfers/173 ('Premium API Access') is entirely opaque. This is effectively a stub listing.
Warnings
- —No documentation available — /docs, /pricing, /api, and /README all show only 'Connect wallet' with no content.
- —No OpenAPI or schema definition found for any endpoint.
- —The purpose and expected request/response format of /api/v1/transfers/173 is undocumented and unclear.
- —The platform lists many endpoint categories (AI, finance, analytics, utils) but none have documented schemas or examples.
Citations
- —The endpoint returns a 402 challenge with maxAmountRequired of 20000 base units of USDC (asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Base networkhttps://lowpaymentfee.com/api/v1/transfers/173
- —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