x402-gated API suite on Base: analytics, AI, finance, and utility endpoints at $0.02/request via USDC.
What it does
lowpaymentfee.com is a multi-category API platform that gates every endpoint behind the x402 payment protocol, settling in USDC on the Base network. The specific endpoint `/api/v1/carts/95` is listed as "Premium API Access" and requires up to 20,000 units of USDC (the asset at 0x8335… on Base, which has 6 decimals, so this equals $0.02) per call via the x402 "exact" scheme. No API keys or rate limits are advertised; callers simply attach an X-PAYMENT header with a valid payment proof.
The broader platform advertises four endpoint families: Data & Analytics (metrics, reports, 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 are priced at $0.02 per request. However, the specific endpoint probed here (`/api/v1/carts/95`) does not clearly map to any of these documented categories — its description is simply "Premium API Access," and no further documentation about what it returns was found.
Documentation is extremely thin. The /docs, /api, /pricing, and /README pages all render only a "Connect wallet" prompt with no substantive content accessible to a crawler. There is no OpenAPI spec, no request/response examples, and no detailed description of what the `/carts/95` endpoint actually does. The endpoint is confirmed live (402 challenge captured), but its actual functionality remains opaque.
Capabilities
Use cases
- —Programmatic access to a pay-per-call API without needing API keys or subscriptions
- —Agent-driven workflows that settle per-request costs in USDC on Base
- —Exploring x402 protocol integration for micropayment-gated services
Fit
Best for
- —Developers experimenting with x402 payment protocol
- —Agents that can sign USDC transactions on Base for per-call billing
- —Users who want keyless, commitment-free API access
Not for
- —Anyone needing detailed documentation or guaranteed SLAs before integrating
- —Use cases requiring free or fiat-settled API access
- —Production workloads that depend on well-documented request/response schemas
Quick start
# The endpoint returns 402 with an x402 challenge.
# Attach a valid X-PAYMENT header (USDC on Base, exact scheme) to access.
curl -X POST https://lowpaymentfee.com/api/v1/carts/95 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <base64-encoded-payment-proof>"Endpoint
Quality
The endpoint is live and returns a valid x402 challenge, but there is no documentation, no OpenAPI spec, no request/response examples, and the purpose of `/api/v1/carts/95` is unclear. The docs pages are empty beyond a wallet-connect prompt. This is effectively a stub listing.
Warnings
- —The specific endpoint /api/v1/carts/95 is not described in the site's listed API categories — its actual functionality is unknown.
- —All documentation pages (/docs, /api, /pricing, /README) returned only a 'Connect wallet' prompt with no usable content.
- —No OpenAPI schema, request format, or response examples are available.
- —The 'carts' path suggests an e-commerce or shopping-cart resource, but this is speculative.
Citations
- —The endpoint returns a 402 challenge with x402Version 1, exact scheme, USDC on Base, maxAmountRequired 20000 (=$0.02)https://lowpaymentfee.com/api/v1/carts/95
- —The platform advertises $0.02/request pricing with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —Four API families are listed: Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructurehttps://lowpaymentfee.com
- —Documentation pages render only a 'Connect wallet' prompthttps://lowpaymentfee.com/docs