x402-gated API platform on Base offering data, AI, finance, and utility endpoints at $0.02/request.
What it does
lowpaymentfee.com is an x402-protocol API marketplace that gates access to a variety of endpoints behind per-request micropayments settled in USDC on the Base network. The specific endpoint at `/api/v1/carts/38` is listed as "Premium API Access" and costs up to $0.02 per call (20,000 base units of USDC with 6 decimals). Payment is handled via the x402 exact scheme — 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 endpoints are listed at the same $0.02 per request price point. The x402 challenge was successfully captured with a 402 response, confirming the endpoint is live.
Note that the specific endpoint `/api/v1/carts/38` does not clearly map to any of the documented API categories on the landing page, and no OpenAPI schema, detailed documentation, or example request/response payloads are available. The docs, pricing, and API pages all render only a "Connect wallet" prompt with no further content. The actual functionality behind this particular cart endpoint is unclear.
Capabilities
Use cases
- —Paying per-request for AI inference (sentiment, summarization, classification, embeddings) without API keys
- —Fetching real-time financial data like token quotes, gas estimates, and exchange rates via micropayment
- —Running data analytics queries and exporting data on demand
- —Geocoding and utility operations with no subscription commitment
Fit
Best for
- —Agents or developers who want keyless, pay-as-you-go API access
- —Low-volume or bursty workloads where subscriptions are wasteful
- —Crypto-native applications already on the Base network
Not for
- —High-volume production workloads needing SLAs and guaranteed uptime
- —Users who need detailed API documentation or OpenAPI specs before integrating
- —Users without access to USDC on Base
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/carts/38 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>" \
-d '{}'Endpoint
Quality
The endpoint is live (402 challenge captured) and pricing is clear ($0.02 USDC on Base), but there is no OpenAPI schema, no documentation beyond a landing page listing, no example requests or responses, and the specific /api/v1/carts/38 path doesn't correspond to any documented endpoint. The docs/pricing/API pages are empty beyond a wallet connect prompt.
Warnings
- —The endpoint path /api/v1/carts/38 does not match any of the documented API endpoints on the landing page — its actual functionality is unknown.
- —No OpenAPI spec, request schema, or response schema is available.
- —Documentation pages (/docs, /pricing, /api, /README) all render only a 'Connect wallet' prompt with no usable content.
- —The platform's actual data sources and AI model details are undisclosed.
Citations
- —The endpoint returns a 402 x402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/carts/38
- —All listed endpoints are priced at $0.02 per request with no API keys, no rate limits, and instant access on the Base networkhttps://lowpaymentfee.com
- —The platform offers endpoints in four categories: Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructurehttps://lowpaymentfee.com
- —USDC asset address 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base networkhttps://lowpaymentfee.com/api/v1/carts/38