Pay-per-request API suite on Base via x402 — data, AI, finance, and utility endpoints at $0.02/call.
What it does
lowpaymentfee.com hosts 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/34` is listed as "Premium API Access" and returns a 402 challenge requesting up to 20,000 base units of USDC (0x8335…2913 on Base), which equals $0.02 per call (USDC uses 6 decimals). Payment is made via the x402 exact scheme with no API keys, subscriptions, or rate limits required.
The broader platform advertises four categories of endpoints: 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 listed at the same $0.02/request price point.
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 spec, no request/response schema documentation, and no usage examples available from the crawl. The specific functionality behind `/api/v1/carts/34` (labeled "Premium API Access") is unclear and does not map to any of the advertised API categories, suggesting it may be a demo or placeholder endpoint.
Capabilities
Use cases
- —Accessing AI inference endpoints (sentiment, summarization, classification, embeddings) without API key management
- —Fetching 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 micropayments
- —Integrating pay-as-you-go data analytics into agent workflows
Fit
Best for
- —AI agents needing low-friction, keyless API access via crypto micropayments
- —Developers prototyping with multiple API categories at minimal cost
- —Applications that need on-demand access without subscription commitments
Not for
- —High-volume production workloads requiring guaranteed SLAs and detailed documentation
- —Users without a Base-network USDC wallet or x402-compatible client
- —Anyone needing well-documented request/response schemas before integration
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/carts/34 \
-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, documentation is essentially nonexistent — all doc pages show only 'Connect wallet'. There is no OpenAPI spec, no request/response examples, and the specific purpose of /api/v1/carts/34 is unclear. The listing is effectively a stub with confirmed liveness.
Warnings
- —Documentation pages (/docs, /api, /pricing, /README) all return only 'Connect wallet' with no technical content
- —No OpenAPI or schema documentation available for any endpoint
- —The endpoint path /api/v1/carts/34 does not correspond to any of the advertised API categories — its actual functionality is unknown
- —No request body schema or response format documented anywhere
Citations
- —The endpoint returns a 402 challenge requesting maxAmountRequired of 20000 base units of USDC on Base networkhttps://lowpaymentfee.com/api/v1/carts/34
- —All listed endpoints are priced at $0.02 per request with no API keys, rate limits, or minimumshttps://lowpaymentfee.com
- —The platform offers endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com
- —USDC contract address on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/carts/34