Pay-per-request API suite on Base via x402 — data, AI, finance, and utility endpoints at $0.02/call.
What it does
lowpaymentfee.com offers a collection of pay-per-request API endpoints settled via the x402 protocol on the Base network using USDC. The specific endpoint `/api/v1/carts/17` is listed as "Premium API Access" and requires a maximum payment of 20,000 base units of USDC (0.02 USD) per call. The broader platform advertises four categories of APIs: 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 with no API keys, no rate limits, and no minimum commitments required. Payments are made via the x402 exact-payment scheme on the Base L2 network, settling in USDC (contract 0x8335…2913). The platform emphasizes low friction: callers attach an X-PAYMENT header to each request and receive the response immediately upon payment verification.
Documentation is extremely sparse — the /docs, /api, /pricing, and /README pages all render only a "Connect wallet" prompt with no further technical detail. There is no OpenAPI specification, no request/response schema documentation, and no usage examples available from the crawled content. The exact functionality behind the `/api/v1/carts/17` endpoint is unclear beyond its "Premium API Access" label.
Capabilities
Use cases
- —Accessing AI inference (sentiment, summarization, classification, embeddings) without API key signup
- —Fetching real-time financial data and crypto gas estimates on a per-request basis
- —Running geocoding or data validation calls with instant crypto-settled billing
- —Exporting analytics data or generating insights via pay-as-you-go endpoints
Fit
Best for
- —Agents or bots that need frictionless, key-free API access settled in crypto
- —Developers prototyping with multiple utility APIs at very low per-call cost
- —Web3-native applications that prefer on-chain USDC micropayments over subscriptions
Not for
- —Users who need detailed API documentation or OpenAPI specs before integrating
- —High-volume production workloads that would benefit from bulk pricing or rate-limit guarantees
- —Teams that require fiat billing or traditional API key authentication
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/carts/17 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live (402 challenge captured) and pricing is clear ($0.02 USDC on Base), but there is no OpenAPI spec, no request/response schema, no documentation beyond a landing page listing, and no examples. The actual functionality of /api/v1/carts/17 is opaque. This is effectively a stub listing.
Warnings
- —No OpenAPI specification or schema documentation available
- —All documentation pages (/docs, /api, /pricing, /README) render only 'Connect wallet' with no technical content
- —The specific purpose and expected input/output of /api/v1/carts/17 ('Premium API Access') is undocumented
- —No request or response examples could be sourced
Citations
- —The endpoint returns a 402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/carts/17
- —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 platform offers APIs across Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com
- —USDC asset contract is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/carts/17