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 USDC micropayments on the Base network. The specific endpoint at `/api/v1/carts/91` is listed as "Premium API Access" and accepts POST requests with payment via the x402 exact scheme. The maximum amount required is 20,000 base units of USDC (0x8335…2913 on Base), which equals $0.02 per request given USDC's 6 decimal places.
The broader platform advertises four categories of APIs: 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. The platform claims no API keys, no rate limits, no minimums, and instant access — payment is handled entirely through the x402 payment header.
Documentation is extremely sparse. The docs, API, pricing, and README pages all render only a "Connect wallet" prompt with no additional content. There is no OpenAPI schema, no request/response examples, and no detailed documentation for what any of the endpoints actually accept or return. The `/api/v1/carts/91` endpoint specifically lacks any description beyond its title, making it unclear what data or functionality it provides. The endpoint is confirmed live (returns a proper 402 challenge), but the actual behavior behind the paywall is unknown.
Capabilities
Use cases
- —Accessing premium API data with per-call USDC micropayments on Base
- —Integrating pay-as-you-go API services without API key management
- —Agent-driven API consumption using x402 payment protocol
Fit
Best for
- —Developers wanting zero-commitment, pay-per-use API access
- —AI agents that can settle x402 payments autonomously on Base
- —Users who prefer crypto micropayments over subscription billing
Not for
- —Users needing detailed API documentation or schemas before purchasing
- —High-volume consumers who would benefit from bulk pricing or subscriptions
- —Anyone without access to USDC on the Base network
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/carts/91 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is confirmed live with a valid x402 402 challenge and clear pricing ($0.02 USDC on Base). However, there is no OpenAPI schema, no documentation, no request/response examples, and no explanation of what the /api/v1/carts/91 endpoint actually does. The docs pages are empty beyond a wallet connect prompt. This is effectively a stub listing.
Warnings
- —No documentation available — all doc pages render only 'Connect wallet' with no content
- —No OpenAPI or request/response schema provided for any endpoint
- —The purpose of /api/v1/carts/91 ('Premium API Access') is completely undocumented
- —Cannot verify what data or functionality is returned after payment
- —The platform lists many endpoint categories but none have documented schemas or examples
Citations
- —The endpoint returns a 402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/carts/91
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/carts/91
- —Platform advertises $0.02/request pricing with no API keys, no rate limits, and no minimumshttps://lowpaymentfee.com
- —Four API categories listed: Data & Analytics, AI & Machine Learning, Finance & Web3, Infrastructurehttps://lowpaymentfee.com