Pay-per-call API platform on Base with USDC payments at $0.02/request via x402.
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/72` is listed as "Premium API Access" and accepts POST requests with payment settled in USDC (contract 0x8335…2913 on Base). The x402 challenge indicates a maximum amount of 20,000 base units, which at 6 decimals for USDC equals $0.02 per request.
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.
However, the specific functionality of the `/api/v1/inbox/72` endpoint is unclear. It does not correspond to any of the named API categories listed on the homepage, and the generic "Premium API Access" description provides no detail about what data or service it returns. There is no OpenAPI schema, no request/response examples, and no documentation beyond the homepage listing. The endpoint is live (returns a valid 402 challenge), but its actual behavior after payment is unknown.
Capabilities
Use cases
- —Programmatic access to a paid API endpoint without requiring API key registration
- —Agent-driven workflows that need to pay per request using 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 in USDC on Base
- —Use cases requiring no-signup, pay-as-you-go API access
Not for
- —Users who need detailed documentation or guaranteed SLAs before integrating
- —Anyone requiring free or fiat-only payment methods
- —Production workloads that depend on well-documented request/response schemas
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/inbox/72 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live and returns a valid x402 402 challenge, confirming pricing and payment details. However, the specific functionality of /api/v1/inbox/72 is entirely undocumented — no OpenAPI schema, no request/response examples, and the generic 'Premium API Access' label gives no indication of what the endpoint actually does. The crawled pages beyond the homepage returned only 'Connect wallet' with no useful content.
Warnings
- —The specific purpose and functionality of /api/v1/inbox/72 is unknown — it does not match any named endpoint on the homepage
- —No OpenAPI schema, request format, or response format documentation is available
- —No example requests or responses could be found
- —The /api, /pricing, and /README pages returned no meaningful content beyond 'Connect wallet'
- —The endpoint path '/inbox/72' suggests a resource-specific or user-specific endpoint whose general utility is unclear
Citations
- —The x402 challenge specifies maxAmountRequired of 20000 base units in USDC (6 decimals) = $0.02 on Base networkhttps://lowpaymentfee.com/api/v1/inbox/72
- —The platform lists uniform pricing of $0.02 per request across all endpoints with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —USDC asset contract is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/inbox/72
- —The platform offers APIs in categories: Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructurehttps://lowpaymentfee.com