Pay-per-call API platform on Base (USDC) covering data, AI, finance, and utility endpoints at $0.02/request.
What it does
lowpaymentfee.com is an x402-enabled API platform that offers a broad catalog of pay-per-request endpoints settled in USDC on the Base network. The specific endpoint `/api/v1/inbox/105` is listed as "Premium API Access" and costs up to $0.02 per call (20,000 base units of USDC with 6 decimals). Payment is handled via the x402 protocol — no API keys, no subscriptions, no rate limits. Callers attach an `X-PAYMENT` header with a signed payment to access the resource.
The broader platform advertises four endpoint 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 uniformly priced at $0.02 per request.
However, the specific functionality behind `/api/v1/inbox/105` is not documented — the path pattern ("inbox/105") does not match any of the publicly listed API routes. No OpenAPI schema, request/response examples, or detailed documentation were found for this endpoint or for the platform generally. The crawled /api, /pricing, and /README pages returned only a "Connect wallet" prompt with no substantive content. The endpoint is confirmed live (returns a valid 402 challenge), but what it actually returns upon successful payment is unknown.
Capabilities
Use cases
- —Accessing premium API data with per-request USDC micropayments on Base
- —Agent-driven workflows that need keyless, pay-as-you-go API access
- —Programmatic access to an inbox or messaging resource behind a paywall
Fit
Best for
- —Developers wanting zero-signup, pay-per-use API access
- —AI agents with x402-compatible wallets on Base
- —Users who prefer crypto micropayments over subscription billing
Not for
- —Users needing well-documented APIs with clear request/response schemas
- —Anyone without a Base-network USDC wallet
- —High-volume use cases where per-request pricing may add up
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/inbox/105 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <signed-x402-payment-header>"Endpoint
Quality
The endpoint is live and returns a valid x402 402 challenge, but there is no documentation, no OpenAPI schema, no request/response examples, and the specific path '/api/v1/inbox/105' does not match any publicly listed route. The actual functionality behind this endpoint is entirely unknown.
Warnings
- —The path /api/v1/inbox/105 does not correspond to any documented endpoint on the platform's landing page.
- —No OpenAPI spec, request schema, or response schema is available for this or any endpoint on the platform.
- —The /api, /pricing, and /README pages returned no useful content beyond a wallet-connect prompt.
- —Actual response payload upon successful payment is unknown — callers are paying blind.
Citations
- —The endpoint returns a valid x402 402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/inbox/105
- —The platform lists endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categories all priced at $0.02/requesthttps://lowpaymentfee.com
- —The platform advertises no API keys, no rate limits, instant access, and Base network settlementhttps://lowpaymentfee.com
- —USDC asset address 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base networkhttps://lowpaymentfee.com/api/v1/inbox/105