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 micropayments settled in USDC on the Base network. The specific endpoint at `/api/v1/cards/90` is listed as "Premium API Access" and costs up to $0.02 per call (maxAmountRequired of 20,000 base units of USDC, which has 6 decimals = $0.02). Payment is handled via the x402 exact scheme — callers attach an X-PAYMENT header with a signed payment to the payTo address, and the server fulfills the request upon verification.
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 $0.02 per request with no API keys, no rate limits, and no minimum commitments required.
Note that the specific endpoint `/api/v1/cards/90` does not clearly map to any of the documented API categories on the landing page. Its actual functionality is unknown — the description simply says "Premium API Access" with no further detail. Documentation pages (/docs, /pricing, /README) returned only a wallet-connect prompt with no substantive content, so the actual request/response schemas and behavior of this endpoint remain unverified.
Capabilities
Use cases
- —Programmatic access to premium API endpoints without traditional API key management
- —Agent-driven workflows that need to pay per call using on-chain USDC on Base
- —Exploring x402 protocol integration for micropayment-gated services
Fit
Best for
- —Developers experimenting with x402 payment protocol
- —AI agents that can autonomously pay for API calls via crypto micropayments
- —Users who want pay-as-you-go access without subscriptions or rate limits
Not for
- —Users who need detailed API documentation and well-defined schemas before integrating
- —High-volume consumers who would benefit from bulk pricing or subscription plans
- —Anyone without a Base-network USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/cards/90 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <signed-x402-payment-header>"Endpoint
Quality
The endpoint is live (returns a valid 402 x402 challenge), but there is no documentation, no request/response schema, and the specific endpoint '/api/v1/cards/90' does not correspond to any documented API on the landing page. All doc/pricing/README pages are empty beyond a wallet-connect prompt. The actual functionality of this endpoint is unknown.
Warnings
- —The endpoint path /api/v1/cards/90 does not match any of the documented API routes on the landing page — its actual functionality is unclear.
- —All documentation pages (/docs, /pricing, /README, /api) returned no substantive content, only a wallet-connect prompt.
- —No request or response schema is available; callers cannot know what to send or what to expect back.
- —The platform lists many API categories but none appear to relate to 'cards' — this may be a test or placeholder endpoint.
Citations
- —The endpoint returns a 402 x402 challenge with maxAmountRequired of 20000 base units of USDC on Base networkhttps://lowpaymentfee.com/api/v1/cards/90
- —USDC asset address 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/cards/90
- —Platform advertises $0.02/request pricing with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —Four API categories listed: Data & Analytics, AI & Machine Learning, Finance & Web3, Infrastructurehttps://lowpaymentfee.com