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-enabled API platform that exposes a variety of endpoints across four categories: 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, payable in USDC on the Base network via the x402 protocol.
The specific endpoint being listed here — `/api/v1/carts/78` — is described 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 given USDC's 6 decimals. Payment is made via the x402 `exact` scheme with a 300-second timeout. The endpoint accepts POST requests and returns `application/json`.
Note that the `/api/v1/carts/78` path does not clearly map to any of the documented API categories on the landing page (data, AI, finance, infrastructure). It may be a cart or bundle endpoint, or a generic access token. Documentation beyond the landing page is extremely thin — the docs, API, pricing, and README pages all render only a "Connect wallet" prompt with no additional content. There is no OpenAPI spec, no request/response schema documentation, and no usage examples available from the crawled material.
Capabilities
Use cases
- —Accessing AI inference endpoints (sentiment, summarization, classification, embeddings) without API keys
- —Fetching real-time financial data like token quotes, gas estimates, and exchange rates on a per-request basis
- —Running data analytics queries and exporting data with per-call micropayments
- —Using utility services like geocoding, validation, and conversion without subscription commitments
Fit
Best for
- —Agents or developers who want keyless, pay-per-use API access
- —Low-volume or bursty workloads where subscription pricing is wasteful
- —x402-compatible agents that can settle USDC payments on Base automatically
Not for
- —High-volume production workloads needing guaranteed SLAs and detailed documentation
- —Users without a Base-compatible USDC wallet or x402 client
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/carts/78 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-header>"Endpoint
Quality
The endpoint is live and returns a valid x402 402 challenge, confirming pricing and payment details. However, there is no OpenAPI spec, no request/response schema, no documentation beyond a landing page listing, and the specific /api/v1/carts/78 path is not explained anywhere. The docs, pricing, and README pages are all blank (wallet-connect only). This is effectively a stub listing.
Warnings
- —The /api/v1/carts/78 endpoint is not documented on the landing page and its purpose is unclear — it may be a generic access or bundle endpoint rather than a specific API function.
- —No OpenAPI spec, request schema, or response schema is available.
- —All documentation pages (docs, API, pricing, README) render only a 'Connect wallet' prompt with no usable content.
- —No examples of request bodies or response payloads are available from any source.
Citations
- —All endpoints are priced at $0.02 per request, payable on the Base network with no API keys, no rate limits, and instant access.https://lowpaymentfee.com
- —The x402 challenge for /api/v1/carts/78 requests up to 20,000 base units of USDC (asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Base, with a 300-second timeout.https://lowpaymentfee.com/api/v1/carts/78
- —Available API categories include Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructure.https://lowpaymentfee.com