Pay-per-call API platform on Base (USDC) via x402 — $0.02/request, no API keys required.
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/payments/328` is listed as "Premium API Access" and costs $0.02 per call (20,000 base units of USDC with 6 decimals). No API keys, accounts, or rate limits are advertised — 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 listed endpoints share the same $0.02/request pricing.
This particular endpoint (`/api/v1/payments/328`) is labeled generically as "Premium API Access" and does not appear in the site's public API catalog, so its specific functionality is unclear. The x402 challenge confirms it is live and accepts POST requests returning application/json. Payment settles to address `0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3` using USDC (`0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913`) on Base.
Capabilities
Use cases
- —Accessing premium API functionality with per-request USDC micropayments on Base
- —Agent-driven workflows that need keyless, on-demand API access
- —Testing x402 protocol integrations with a low-cost endpoint
Fit
Best for
- —Developers experimenting with x402 payment protocol
- —AI agents that need frictionless pay-per-call API access without credentials
- —Users who want to avoid subscriptions and pay only for what they use
Not for
- —Users who need detailed documentation or OpenAPI schemas before integrating
- —High-volume consumers who would benefit from bulk pricing or subscriptions
- —Anyone without a Base-network USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/payments/328 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-proof>"Endpoint
Quality
The x402 challenge is live and pricing is clear ($0.02 USDC on Base), but the specific endpoint's functionality is undocumented — it doesn't appear in the site catalog, there's no OpenAPI spec, no request/response schema, and the docs/pricing/README pages are all empty (just 'Connect wallet'). The listing is essentially a stub with confirmed liveness.
Warnings
- —The endpoint /api/v1/payments/328 is not listed in the site's public API catalog; its actual functionality is unknown.
- —No OpenAPI spec, request schema, or response schema is available — callers cannot know what to send or expect back.
- —All documentation pages (docs, pricing, README, api) returned only 'Connect wallet' with no useful content.
- —The platform's broader API offerings (AI, analytics, finance, utils) are unverified — only this single endpoint was probed.
Citations
- —The endpoint returns a 402 x402 challenge requesting 20,000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/payments/328
- —USDC contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 with 6 decimalshttps://lowpaymentfee.com/api/v1/payments/328
- —Platform advertises $0.02/request pricing with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —Site lists endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com