x402-gated API platform on Base offering data, AI, finance, and utility endpoints at $0.02/request.
What it does
lowpaymentfee.com is an x402-protocol API marketplace that gates a collection of endpoints behind per-request USDC micropayments on the Base network. The specific endpoint at `/api/v1/inbox/114` is listed as "Premium API Access" and accepts POST requests with an x402 payment header. The site advertises four broad categories of APIs: 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).
Pricing across the platform is uniform at $0.02 per request (20,000 base units of USDC with 6 decimals = $0.02), settled in USDC on the Base L2 network. The platform advertises no API keys, no rate limits, no minimums, and instant access — callers simply attach an x402 payment header to each request. The x402 challenge captured from the probed endpoint confirms the endpoint is live, using the "exact" payment scheme with a maxAmountRequired of 20,000 base units (~$0.02) and a 300-second payment timeout.
Note that the specific functionality behind `/api/v1/inbox/114` is not documented on the site's landing page, which lists other named endpoints but not this one. Without further documentation or an OpenAPI spec, the exact input/output schema for this endpoint is unknown. The broader platform pages (pricing, README, API docs) returned only a "Connect wallet" prompt with no additional content.
Capabilities
Use cases
- —Agents that need on-demand API access without pre-registration or API keys
- —Programmatic access to data, AI, or finance endpoints with per-call crypto payment
- —Testing x402 protocol integrations with a low-cost live endpoint
- —Accessing utility services (geocoding, validation, conversion) via micropayments
Fit
Best for
- —Developers or agents wanting zero-signup, pay-per-call API access
- —x402 protocol experimentation at very low cost ($0.02/call)
- —Crypto-native applications already operating on Base with USDC
Not for
- —Users who need detailed API documentation or OpenAPI schemas before integrating
- —High-volume use cases where per-request payment overhead is impractical
- —Users without a Base-network USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/inbox/114 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>" \
-d '{}'Endpoint
Quality
The endpoint is live (402 challenge confirmed) and pricing is clear ($0.02 USDC on Base), but there is no OpenAPI spec, no documentation for this specific endpoint (/api/v1/inbox/114), no input/output schema, and no example responses. The broader site docs pages returned only wallet-connect prompts. The listing is effectively a stub with confirmed liveness.
Warnings
- —No OpenAPI or schema documentation available for this endpoint
- —The specific path /api/v1/inbox/114 is not listed among the site's advertised APIs — its exact functionality is unknown
- —Site documentation pages (/api, /pricing, /README) returned no useful content beyond a wallet-connect prompt
- —No example request or response bodies are available
Citations
- —The platform advertises APIs across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categories, all at $0.02/requesthttps://lowpaymentfee.com
- —Pricing is $0.02 per request with no API keys, no rate limits, no minimums, on the Base networkhttps://lowpaymentfee.com
- —The x402 challenge for /api/v1/inbox/114 shows maxAmountRequired of 20000 base units of USDC (0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Base with a 300-second timeouthttps://lowpaymentfee.com/api/v1/inbox/114