Pay-per-call API suite for analytics, AI, finance, and utilities via x402 on Base.
What it does
lowpaymentfee.com exposes a collection of HTTP APIs gated by the x402 payment protocol on the Base network. The specific endpoint probed (`/_dot_git`) returns a 402 challenge requesting payment in USDC (contract 0x8335…2913) on Base, with a maxAmountRequired of 20,000 base units — which, at 6 decimals for USDC, equals $0.02 per request.
The site 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 endpoints are listed at $0.02 per request with no API keys, no rate limits, and no minimum commitments required. Payment settles in USDC on the Base L2 network using the x402 "exact" scheme.
Documentation is extremely thin — the /docs, /api, /pricing, and /README pages all resolve to a minimal "Connect wallet" prompt with no further technical detail. There is no OpenAPI spec, no request/response schema documentation, and no usage examples available from the crawl. The actual behavior and output of each endpoint cannot be verified from the available material.
Capabilities
Use cases
- —Running sentiment analysis or text summarization without managing API keys
- —Fetching real-time crypto gas estimates or token quotes with per-call payment
- —Geocoding addresses or validating data via a keyless, pay-as-you-go endpoint
- —Exporting analytics data or generating reports on demand
Fit
Best for
- —Agents or developers who want keyless, per-call API access settled on-chain
- —Low-volume or bursty workloads where $0.02/request is cost-effective
- —x402-compatible wallets and agent frameworks on the Base network
Not for
- —High-volume production workloads where $0.02/request adds up quickly
- —Users who need detailed API documentation, SLAs, or guaranteed uptime
- —Anyone without a Base-compatible wallet or x402 client
Quick start
curl -X POST https://lowpaymentfee.com/api/v2/ai/sentiment \
-H "X-PAYMENT: <x402-payment-token>" \
-H "Content-Type: application/json" \
-d '{"text": "This product is amazing!"}'Endpoint
Quality
The endpoint is live (402 challenge confirmed) and pricing is clear ($0.02 USDC on Base per call), but there is no OpenAPI spec, no request/response schemas, no examples, and all documentation pages return only a 'Connect wallet' stub. The breadth of advertised endpoints cannot be verified.
Warnings
- —No OpenAPI or schema documentation available for any endpoint
- —All doc/pricing/README pages return only a 'Connect wallet' prompt with no content
- —The probed path /_dot_git is unusual and may be a git directory exposure test rather than a real API resource
- —Actual endpoint behavior and response formats are completely undocumented
- —Cannot verify that the 16 advertised API endpoints actually function
Citations
- —The x402 challenge requests 20,000 base units of USDC on Base (=$0.02) per requesthttps://lowpaymentfee.com/_dot_git
- —USDC asset contract is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/_dot_git
- —Site advertises 16 endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categories, all at $0.02/requesthttps://lowpaymentfee.com
- —No API keys, no rate limits, instant access advertisedhttps://lowpaymentfee.com
- —Documentation pages (/docs, /api, /pricing, /README) show only 'Connect wallet'https://lowpaymentfee.com/docs