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 at `/api/v1/cards/63` 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 subscriptions required.
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 per request price point.
Documentation is extremely sparse — the docs, API, pricing, and README pages all render only a "Connect wallet" prompt with no further content. There is no OpenAPI schema, no request/response examples, and no detailed documentation for any endpoint. The specific functionality behind `/api/v1/cards/63` ("Premium API Access") is not described beyond its title, so its actual behavior is unknown. The endpoint is live and returns a valid x402 402 challenge.
Capabilities
Use cases
- —Accessing premium API endpoints without creating accounts or managing API keys
- —Making one-off data or AI inference requests with per-call USDC micropayments
- —Integrating pay-as-you-go API calls into autonomous agent workflows on Base
Fit
Best for
- —Developers wanting frictionless, keyless API access via crypto micropayments
- —AI agents that need to autonomously purchase API calls on the Base network
- —Projects needing low-cost per-request pricing without subscriptions
Not for
- —Users who need detailed API documentation or OpenAPI specs before integrating
- —High-volume consumers who prefer flat-rate or subscription pricing
- —Developers without access to USDC on the Base network
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/cards/63 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live and returns a valid x402 402 challenge, but there is zero documentation beyond the endpoint title. No OpenAPI schema, no request/response examples, and no description of what '/api/v1/cards/63' actually returns. The docs pages are empty ('Connect wallet' only). The listing is effectively a stub.
Warnings
- —No documentation available — docs, API, pricing, and README pages all show only 'Connect wallet'
- —The specific functionality of /api/v1/cards/63 ('Premium API Access') is completely undocumented
- —No OpenAPI schema or request/response examples are provided
- —No way to verify what data or service is actually returned after payment
Citations
- —The endpoint returns a valid x402 402 challenge with maxAmountRequired of 20000 in USDC on Basehttps://lowpaymentfee.com/api/v1/cards/63
- —All 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 offers APIs across Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com
- —USDC asset address 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base networkhttps://lowpaymentfee.com/api/v1/cards/63