Pay-per-call API platform on Base network via x402 — $0.02/request for data, AI, finance, and utility endpoints.
What it does
lowpaymentfee.com is an x402-enabled API platform that offers a broad catalog of pay-per-request endpoints settled in USDC on the Base network. The specific endpoint at `/api/v1/transactions/50` is listed as "Premium API Access" and accepts x402 payments with a maximum cost of 20,000 base units of USDC (i.e., $0.02 per request). No API keys or rate limits are advertised — callers simply attach an x402 payment header to each request.
The platform organizes its endpoints into four categories: 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 are priced uniformly at $0.02 per call.
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 description of what the `/api/v1/transactions/50` endpoint specifically returns. The x402 challenge confirms the endpoint is live and accepts POST requests, but the actual payload format and response structure are unknown.
Capabilities
Use cases
- —Accessing AI inference endpoints (sentiment, summarization, classification, embeddings) without API key management
- —Fetching real-time financial data like token quotes, exchange rates, and gas estimates on a per-call basis
- —Running utility operations like geocoding, validation, and data conversion with micropayments
Fit
Best for
- —Agents or applications that need simple pay-per-call API access without subscriptions
- —Developers wanting to avoid API key provisioning and rate limit management
- —x402-compatible clients on the Base network looking for low-cost endpoints
Not for
- —Users who need detailed API documentation or guaranteed SLAs before integrating
- —High-volume consumers who would benefit from bulk pricing or subscription models
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/transactions/50 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The x402 challenge confirms the endpoint is live and pricing is clear ($0.02/request in USDC on Base). However, there is no OpenAPI schema, no request/response examples, and all documentation pages render only 'Connect wallet' with no useful content. The purpose of the specific /api/v1/transactions/50 endpoint is unclear beyond its generic 'Premium API Access' label.
Warnings
- —No API documentation available — all doc pages show only 'Connect wallet'
- —No OpenAPI or JSON schema describing request/response formats
- —The specific purpose of /api/v1/transactions/50 is undocumented
- —No examples of expected input or output for any endpoint
- —The broad catalog of endpoints (AI, finance, data, utils) is listed but none have detailed descriptions
Citations
- —The endpoint returns a 402 challenge with maxAmountRequired of 20000 base units of USDC on Base networkhttps://lowpaymentfee.com/api/v1/transactions/50
- —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 endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com
- —USDC asset address is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/transactions/50