Pay-per-call API platform on Base network via x402 — $0.02/request in USDC.
What it does
lowpaymentfee.com is an x402-enabled API marketplace that offers a variety of endpoints across data analytics, AI/ML inference, finance/Web3, and infrastructure utilities. All endpoints are priced at $0.02 per request, payable in USDC on the Base network with no API keys, no rate limits, and no commitments required. The x402 protocol handles payment inline: callers attach a payment header to each request and receive the response immediately upon settlement.
The specific endpoint at `/api/v1/charges/376` is listed as "Premium API Access" and returns a 402 challenge requesting up to 20,000 base units of USDC (0x8335…2913 on Base). Since USDC uses 6 decimals, this equals $0.02 per call — consistent with the site's advertised flat pricing. Payment is via the "exact" scheme with a 300-second timeout. The endpoint accepts POST requests and returns application/json.
The broader platform advertises endpoints for sentiment analysis, text summarization, classification, embeddings, price feeds, exchange rates, token quotes, gas estimates, geocoding, validation, conversion, and generation. However, documentation beyond the landing page is essentially empty (all doc/pricing/API pages only show a "Connect wallet" prompt), so the actual capabilities and response schemas of individual endpoints are unverified.
Capabilities
Use cases
- —Agents that need on-demand API access without pre-registration or API keys
- —Paying per-call for AI inference (sentiment, summarization, classification, embeddings)
- —Fetching real-time crypto prices, gas estimates, or exchange rates with micropayments
- —Geocoding or data validation without subscription commitments
Fit
Best for
- —AI agents needing keyless, pay-as-you-go API access
- —Developers prototyping with low-cost per-request pricing on Base
- —Web3-native applications that already hold USDC on Base
Not for
- —High-volume production workloads needing guaranteed SLAs (no documentation on uptime or support)
- —Users without USDC on Base network or unfamiliar with x402 protocol
- —Applications requiring detailed API documentation or response schema guarantees
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/charges/376 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-header>"Endpoint
Quality
The endpoint is live and returns a valid 402 challenge with clear pricing. However, documentation is effectively nonexistent — all doc pages render only 'Connect wallet'. There is no OpenAPI schema, no example requests/responses, and no description of what 'Premium API Access' actually returns. The listing is largely a stub.
Warnings
- —Documentation pages (/docs, /pricing, /api, /README) are all empty beyond a 'Connect wallet' prompt — no usable API docs exist.
- —No OpenAPI or schema available; actual request parameters and response format for /api/v1/charges/376 are unknown.
- —The endpoint name 'Premium API Access' is generic and does not describe what data or service is returned.
- —The broader platform lists many endpoints (AI, finance, utils) but none have documented schemas or verified functionality.
Citations
- —All endpoints priced at $0.02 per request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —x402 challenge returns maxAmountRequired of 20000 base units of USDC (0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Base, equaling $0.02https://lowpaymentfee.com/api/v1/charges/376
- —Platform offers endpoints across Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com