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 accessible via the x402 payment protocol on the Base network. The specific endpoint at `/api/v1/carts/60` is labeled "Premium API Access" and requires a payment of up to 20,000 base units of USDC (0x8335…2913 on Base, 6 decimals = $0.02) per call. Payment is settled on-chain with no API keys, no rate limits, and no subscriptions 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 listed endpoints share the same $0.02/request pricing. The x402 challenge was successfully captured on the `/api/v1/carts/60` endpoint, confirming it is live and accepting POST requests.
Documentation beyond the landing page 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 example payloads available. The exact functionality behind the "Premium API Access" label at `/api/v1/carts/60` is unclear; it may be a cart or e-commerce related endpoint, but this is not documented.
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-request basis
- —Running utility operations like geocoding or data validation with instant crypto-settled payments
- —Integrating pay-per-use data analytics into agent workflows
Fit
Best for
- —Agents or developers who want zero-signup, pay-as-you-go API access
- —Crypto-native applications that can settle USDC on Base
- —Low-volume or bursty workloads where subscription pricing is wasteful
Not for
- —Users who need detailed API documentation or OpenAPI specs before integrating
- —High-volume production workloads requiring SLAs, rate-limit guarantees, or support contracts
- —Developers without a Base-compatible wallet or USDC holdings
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/carts/60 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>" \
-d '{}'Endpoint
Quality
The x402 challenge is live and confirms pricing and network details, but there is zero documentation for request/response schemas, no OpenAPI spec, and the specific purpose of the /api/v1/carts/60 endpoint is undocumented. All secondary pages return only a wallet-connect prompt. This is effectively a stub listing.
Warnings
- —No OpenAPI spec or request/response schema available for any endpoint
- —Documentation pages (/docs, /api, /pricing, /README) are empty beyond a wallet-connect prompt
- —The specific functionality of /api/v1/carts/60 ('Premium API Access') is not documented — unclear what it returns
- —The breadth of advertised endpoints (AI, finance, data, utils) could not be independently verified beyond the landing page listing
Citations
- —The endpoint returns a 402 challenge requiring up to 20,000 base units of USDC on Base networkhttps://lowpaymentfee.com/api/v1/carts/60
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/carts/60
- —All listed endpoints are priced at $0.02 per request with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —The platform advertises endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com