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/142` 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/142`) is labeled generically as "Premium API Access" and does not appear in the site's public API catalog. There is no documentation, OpenAPI schema, or example request/response available for this endpoint, so its actual functionality is unclear. The docs, pricing, and README pages all returned only a "Connect wallet" prompt with no substantive content.
Capabilities
Use cases
- —Programmatic access to a paid API endpoint without traditional API key registration
- —Agent-driven workflows that need to pay per call using on-chain USDC on Base
- —Testing x402 protocol integrations with a low-cost endpoint
Fit
Best for
- —Developers experimenting with x402 payment protocol
- —AI agents that can settle micropayments on Base in USDC
- —Use cases requiring keyless, pay-as-you-go API access
Not for
- —Users who need detailed API documentation or schemas before integrating
- —High-volume callers who prefer subscription-based pricing over per-request charges
- —Anyone needing a clearly defined, well-documented API contract
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/charges/142 \
-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 OpenAPI schema, no example requests or responses, and the specific endpoint does not appear in the site's own catalog. The docs/pricing/README pages are all empty beyond a wallet connect prompt. Functionality is essentially unknown.
Warnings
- —No OpenAPI or schema documentation available for this endpoint
- —The endpoint path /api/v1/charges/142 does not appear in the site's public API catalog — its actual functionality is unknown
- —All documentation pages (docs, pricing, README) returned only 'Connect wallet' with no content
- —No example request or response bodies are available to confirm what this endpoint actually does
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/142
- —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/142