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/charges/375` 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 listed at the same $0.02/request price point.
However, the specific endpoint being listed here (`/api/v1/charges/375`) is labeled generically as "Premium API Access" and does not appear in the site's published API catalog. There is no documentation describing what this particular endpoint returns, what input it expects, or what its output schema looks like. The docs, pricing, and API pages all rendered as empty wallet-connect prompts with no substantive content. As a result, the actual functionality behind this endpoint is unknown.
Capabilities
Use cases
- —Programmatic access to a pay-per-call API without needing API keys or subscriptions
- —Agent-driven workflows that settle per-request costs in USDC on Base
- —Testing x402 protocol integrations with a low-cost endpoint
Fit
Best for
- —Developers exploring x402 payment protocol integrations
- —AI agents that need keyless, pay-as-you-go API access
- —Low-volume callers who want to avoid subscription commitments
Not for
- —Users who need well-documented, production-grade API endpoints with clear schemas
- —High-volume use cases where $0.02/request adds up without bulk discounts
- —Anyone requiring non-crypto payment methods
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/charges/375 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-proof>"Endpoint
Quality
The endpoint is live and returns a valid x402 402 challenge, but there is no documentation, no OpenAPI schema, no example requests or responses, and the specific endpoint path (/api/v1/charges/375) does not appear in the site's own catalog. The docs/pricing/API pages are all empty wallet-connect stubs. The actual functionality behind this endpoint is entirely unknown.
Warnings
- —The endpoint /api/v1/charges/375 is not listed in the site's published API catalog — its purpose is unclear.
- —All documentation pages (docs, pricing, API, README) returned only a 'Connect wallet' prompt with no substantive content.
- —No input or output schema is available; callers cannot know what to send or what to expect back.
- —The platform's broader API offerings (AI, analytics, finance, etc.) are unverified — no docs confirm they actually function.
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/charges/375
- —The platform lists endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categories, all at $0.02/requesthttps://lowpaymentfee.com
- —The platform advertises no API keys, no rate limits, instant access, and Base network settlementhttps://lowpaymentfee.com
- —The USDC asset address is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/charges/375