Pay-per-call API platform on Base network via x402 — $0.02/request in USDC.
What it does
lowpaymentfee.com is a pay-per-request API platform that uses the x402 protocol to accept USDC payments on the Base network. The specific endpoint at `/api/v1/transactions/311` is listed as "Premium API Access" and returns a 402 challenge requesting up to 20,000 base units of USDC (i.e., $0.02) per call. The platform advertises no API keys, no rate limits, and instant access — callers simply attach an X-PAYMENT header with a valid x402 payment proof.
The broader platform offers endpoints across 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 endpoints are priced at $0.02 per request.
The specific functionality behind `/api/v1/transactions/311` is not documented beyond the label "Premium API Access." The crawled docs, pricing, and API pages returned only a "Connect wallet" prompt with no further detail. Without documentation or example responses, the exact data returned by this endpoint is unknown. The output schema indicates it accepts HTTP POST requests and is discoverable.
Capabilities
Use cases
- —Accessing premium API data without needing API key registration
- —Making one-off paid API calls settled in USDC on Base
- —Agent-driven workflows that need keyless, pay-as-you-go API access
Fit
Best for
- —Developers who want instant API access without signup or API keys
- —AI agents that can settle x402 payments autonomously
- —Users comfortable paying in USDC on the Base L2 network
Not for
- —Users who need detailed API documentation or guaranteed SLAs before purchasing
- —Anyone who cannot transact in USDC on the Base network
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/transactions/311 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-proof>"Endpoint
Quality
The endpoint is live (402 challenge confirmed) and pricing is clear ($0.02 USDC on Base), but there is no documentation, no request/response schema, and no explanation of what data 'Premium API Access' actually returns. The docs, pricing, and API pages all resolve to a bare 'Connect wallet' prompt with no useful content.
Warnings
- —The exact functionality of /api/v1/transactions/311 ('Premium API Access') is undocumented — it is unclear what data or service this endpoint provides.
- —Documentation pages (/docs, /api, /pricing, /README) returned no meaningful content beyond 'Connect wallet'.
- —No OpenAPI spec, request schema, or response examples are available.
- —The platform lists many endpoint categories (AI, analytics, finance, infrastructure) but none have public documentation confirming they are functional.
Citations
- —The endpoint returns a 402 challenge requesting up to 20,000 base units of USDC ($0.02) on Base networkhttps://lowpaymentfee.com/api/v1/transactions/311
- —All endpoints are priced at $0.02 per request with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —The platform offers endpoints in Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com
- —USDC asset address 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base networkhttps://lowpaymentfee.com/api/v1/transactions/311