x402-gated API suite on Base: analytics, AI, finance, and utility endpoints at $0.02/request.
What it does
lowpaymentfee.com offers a collection of pay-per-call API endpoints gated by the x402 protocol on the Base network. The specific endpoint `/api/v1/cards/10` is listed as "Premium API Access" and accepts payment in USDC (contract 0x8335…2913 on Base). The x402 challenge advertises a maxAmountRequired of 20,000 base units, which at 6 decimals for USDC equals $0.02 per request.
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 are listed at the same $0.02/request price point.
The platform emphasizes simplicity: no API keys, no rate limits, no minimum commitments, and instant access. Payment is settled on the Base L2 network using USDC. However, documentation beyond the landing page is essentially empty (all sub-pages just show "Connect wallet"), so there is no schema documentation, request/response examples, or detailed endpoint descriptions available. The exact functionality of the `/api/v1/cards/10` endpoint specifically is unclear from the available material.
Capabilities
Use cases
- —Paying per-call for AI inference (sentiment, summarization, classification, embeddings) without API key management
- —Fetching real-time financial data like token quotes, gas estimates, and exchange rates on demand
- —Running analytics queries and data exports with micropayment-based access control
- —Geocoding, validation, and data conversion via utility endpoints
Fit
Best for
- —Agents or apps that need simple pay-per-use API access without subscriptions
- —Developers wanting x402-native endpoints on Base with USDC settlement
- —Low-volume or bursty workloads where $0.02/request is cost-effective
Not for
- —High-volume production workloads where per-request micropayments add overhead
- —Users who need detailed API documentation, SDKs, or guaranteed SLAs
- —Anyone without a Base-compatible USDC wallet
Quick start
# POST with x402 payment header (pseudocode)
curl -X POST https://lowpaymentfee.com/api/v1/cards/10 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live (402 challenge confirmed) and pricing is clear ($0.02 USDC on Base), but there is no API documentation, no request/response schemas, no examples, and the specific purpose of /api/v1/cards/10 is unexplained. All doc pages return only 'Connect wallet' with no useful content.
Warnings
- —No API documentation available — all doc/pricing/README pages are empty (just show 'Connect wallet')
- —The specific purpose and expected input/output of /api/v1/cards/10 is undocumented
- —No OpenAPI spec, no request schema, no response schema provided
- —The broad claims (AI, analytics, finance endpoints) cannot be independently verified from the crawl
Citations
- —The x402 challenge returns maxAmountRequired of 20000 base units in USDC on Base networkhttps://lowpaymentfee.com/api/v1/cards/10
- —USDC contract address is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/cards/10
- —All endpoints are listed at $0.02/request with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —Platform offers endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com