Pay-per-call API platform on Base (USDC) — $0.02/request, no keys or rate limits.
What it does
lowpaymentfee.com is an x402-enabled API platform that offers a broad catalog of endpoints spanning data analytics, AI/ML inference, finance/Web3 data, and utility/infrastructure services. Every endpoint costs $0.02 per request, paid in USDC on the Base network via the x402 protocol. There are no API keys, no rate limits, and no minimum commitments — callers simply attach an x402 payment header to each request.
The specific endpoint `/api/v1/inbox/107` is listed as "Premium API Access" and returns a 402 challenge requesting up to 20,000 base units of USDC (0x8335…) on Base, which equals $0.02 (USDC uses 6 decimals). The payment is sent to address 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3 with a 300-second timeout. The endpoint accepts POST requests and returns application/json.
Note that while the platform advertises many endpoint categories (sentiment analysis, text summarization, embeddings, price feeds, geocoding, etc.), there is no public documentation describing request/response schemas for any individual endpoint, including this one. The "inbox/107" path does not map to any of the named endpoints on the landing page, so its exact functionality is unclear. Treat this as a generic entry point whose behavior must be discovered by calling it with a valid payment.
Capabilities
Use cases
- —Programmatic access to paid API endpoints without managing API keys
- —Agent-driven workflows that need on-demand, per-call billing via x402
- —Exploring x402 payment protocol integration with USDC on Base
Fit
Best for
- —Developers experimenting with x402 micropayment protocols
- —AI agents that need keyless, pay-as-you-go API access
- —Projects wanting to avoid subscription commitments for low-volume API usage
Not for
- —Production workloads requiring well-documented, schema-validated APIs
- —Users who need free or traditional API-key-based access
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/inbox/107 \
-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 zero documentation on what /api/v1/inbox/107 actually does, no request/response schema, and no examples. The 'inbox/107' path doesn't match any named endpoint on the site. This is effectively a stub listing.
Warnings
- —No documentation exists for the /api/v1/inbox/107 endpoint — its purpose is unknown
- —No request or response schema is available for any endpoint on the platform
- —The 'inbox/107' path does not correspond to any of the named API categories on the landing page
- —Crawled /api, /pricing, and /README pages returned only 'Connect wallet' with no useful content
Citations
- —All endpoints cost $0.02 per request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —The 402 challenge for /api/v1/inbox/107 requests maxAmountRequired of 20000 base units of USDC (asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Basehttps://lowpaymentfee.com/api/v1/inbox/107
- —Platform offers endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com