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 a variety of endpoints behind per-request micropayments settled in USDC on the Base network. The specific endpoint `/api/v1/cards/95` is listed as "Premium API Access" and costs $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 upfront commitments are required. The caller simply includes an X-PAYMENT header with a valid payment proof.
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.
Documentation 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 specific functionality behind `/api/v1/cards/95` ("Premium API Access") is not described beyond its title, making it unclear what data or service it returns. The endpoint is confirmed live via a valid 402 challenge.
Capabilities
Use cases
- —Accessing AI inference endpoints (sentiment, summarization, classification, embeddings) without API key signup
- —Fetching real-time financial data like token quotes, gas estimates, and exchange rates on a per-call basis
- —Running utility operations such as geocoding, validation, and data conversion with instant pay-per-use billing
- —Integrating data analytics and export capabilities into agent workflows via x402 micropayments
Fit
Best for
- —AI agents that need on-demand API access without pre-registration
- —Developers prototyping with multiple API categories under a single payment model
- —Low-volume or bursty workloads where per-request pricing avoids subscription overhead
Not for
- —High-volume production workloads where $0.02/request adds up significantly
- —Users who need detailed API documentation, schemas, or SLAs before integration
- —Applications requiring non-USDC or non-Base-network payment settlement
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/cards/95 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-proof>"Endpoint
Quality
The endpoint is confirmed live via a valid x402 402 challenge, and pricing is clear ($0.02 USDC on Base). However, there is no OpenAPI spec, no request/response schema, no documentation beyond a wallet-connect prompt, and the specific purpose of /api/v1/cards/95 is entirely undescribed. This is effectively a stub listing.
Warnings
- —No API documentation available — /docs, /api, /pricing, and /README all show only 'Connect wallet'
- —No OpenAPI or schema definition found for any endpoint
- —The specific functionality of /api/v1/cards/95 ('Premium API Access') is not described anywhere
- —The broad range of advertised endpoints (AI, finance, data, utils) cannot be verified for actual functionality
Citations
- —The endpoint returns a valid x402 402 challenge with maxAmountRequired of 20000 USDC base units on Base networkhttps://lowpaymentfee.com/api/v1/cards/95
- —All listed endpoints are priced at $0.02 per request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —The platform advertises four categories: Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructurehttps://lowpaymentfee.com
- —USDC asset address 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base networkhttps://lowpaymentfee.com/api/v1/cards/95