Pay-per-request API platform on Base (USDC) via x402 — $0.02/call, 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/inbox/163` is listed as "Premium API Access" and accepts POST requests with payment via USDC (contract 0x8335…2913 on Base). The maximum amount required per call is 20,000 base units of USDC (6 decimals), which equals $0.02 USD.
The broader platform advertises multiple API categories including 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. The platform emphasizes no API keys, no rate limits, no minimums, and instant access — payment is handled entirely through the x402 payment header.
This particular endpoint (`/api/v1/inbox/163`) is confirmed live, returning a proper 402 challenge. However, the specific functionality behind this "Premium API Access" endpoint is not documented beyond its title. The platform's crawled pages beyond the homepage returned only "Connect wallet" prompts with no additional documentation, schemas, or usage examples.
Capabilities
Use cases
- —Accessing premium API endpoints without traditional API key registration
- —Making one-off paid API calls settled in USDC on Base
- —Agent-driven workflows that need instant, keyless API access with crypto payment
Fit
Best for
- —Developers who want pay-as-you-go API access without subscriptions
- —AI agents that can settle x402 payments autonomously on Base
- —Users who prefer crypto-native payment rails over credit card billing
Not for
- —Users who need detailed API documentation or OpenAPI schemas before integrating
- —High-volume consumers who would benefit from bulk pricing or rate-limited tiers
- —Anyone without access to USDC on the Base network
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/inbox/163 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>" \
-d '{}'Endpoint
Quality
The endpoint is confirmed live via a valid 402 challenge, and pricing is clear ($0.02/request in USDC on Base). However, there is no documentation for what this specific endpoint does, no request/response schema, no examples, and the crawled pages beyond the homepage are empty. The endpoint title 'Premium API Access' is generic and uninformative.
Warnings
- —No documentation exists for the specific /api/v1/inbox/163 endpoint — its actual functionality is unknown
- —No OpenAPI spec, request schema, or response schema is available
- —Crawled subpages (/api, /pricing, /README) returned only 'Connect wallet' with no useful content
- —The endpoint name 'Premium API Access' is generic and does not describe what the endpoint does
Citations
- —The endpoint returns a 402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/inbox/163
- —All endpoints are priced at $0.02 per request with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/inbox/163
- —Platform offers APIs across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com