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 `/api/v1/transfers/4` is listed as "Premium API Access" and returns a 402 challenge requesting up to 20,000 base units of USDC (i.e., $0.02 given USDC's 6 decimals) 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 lowpaymentfee.com platform offers multiple API categories including 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.
The `/api/v1/transfers/4` endpoint itself is labeled generically as "Premium API Access" and does not appear in the site's public API listing, so its specific functionality is unclear. It accepts POST requests and returns `application/json`. The payment is settled to address `0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3` using USDC (`0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913`) on Base.
Capabilities
Use cases
- —Accessing premium API endpoints without API key registration
- —Making one-off paid API calls settled in USDC on Base
- —Agent-driven workflows that need instant, keyless API access
Fit
Best for
- —Developers who want keyless, pay-per-use API access
- —AI agents that can settle x402 payments autonomously
- —Users already holding USDC on Base network
Not for
- —Users who need free or subscription-based API access
- —Callers without USDC on the Base network
- —Production workloads requiring SLA guarantees (no documented SLA)
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/transfers/4 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-proof>"Endpoint
Quality
The endpoint is live (402 challenge captured) and pricing is clear ($0.02 USDC on Base), but the specific functionality of /api/v1/transfers/4 is undocumented — it doesn't appear in the site's public API listing. No OpenAPI schema, no request/response examples, and docs/pricing/README pages all render only a wallet-connect prompt with no useful content.
Warnings
- —The specific endpoint /api/v1/transfers/4 is not listed on the provider's public API catalog — its actual functionality is unknown.
- —Documentation pages (/docs, /pricing, /README, /api) returned no meaningful content beyond a 'Connect wallet' prompt.
- —No OpenAPI spec or request/response schema available — input format and output structure are entirely unknown.
- —No SLA, rate-limit, or uptime guarantees documented.
Citations
- —The endpoint returns a 402 challenge requesting up to 20,000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/transfers/4
- —USDC asset address is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/transfers/4
- —Platform advertises $0.02/request, no API keys, no rate limits, instant accesshttps://lowpaymentfee.com
- —Platform offers APIs across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com