Pay-per-call API platform on Base (USDC) offering data, AI, finance, and utility endpoints at $0.02/request.
What it does
lowpaymentfee.com is an x402-enabled API platform that hosts a broad catalog of pay-per-request endpoints across four 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 priced at $0.02 per request, settled in USDC on the Base network via the x402 protocol.
The specific endpoint `/api/v1/inbox/15` is listed as "Premium API Access." Its x402 challenge advertises a maxAmountRequired of 20,000 base units of USDC (0x8335… on Base), which equals $0.02 given USDC's 6 decimals. Payment is made via the x402 exact scheme with no API keys, no rate limits, and no subscriptions required — callers simply attach an X-PAYMENT header to each POST request.
Documentation is minimal: the site's landing page lists available endpoints and pricing, but the /api, /pricing, and /README pages all resolve to a wallet-connect prompt with no further content. There is no OpenAPI spec, no request/response schema documentation, and no usage examples. The purpose of the `/api/v1/inbox/15` endpoint specifically is unclear — it does not appear in the site's public catalog, so its functionality cannot be confirmed from available materials.
Capabilities
Use cases
- —Accessing pay-per-call API services without subscriptions or API keys
- —Making micropayment-gated HTTP requests settled on Base L2 in USDC
- —Integrating agent-purchasable endpoints into automated workflows
Fit
Best for
- —Developers wanting zero-commitment, pay-as-you-go API access
- —AI agents that can settle x402 payments autonomously on Base
- —Projects needing low-cost per-request pricing without rate limits
Not for
- —Users who need detailed API documentation or OpenAPI specs before integrating
- —High-volume consumers who would benefit from bulk/subscription pricing
- —Anyone unable to pay in USDC on the Base network
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/inbox/15 \
-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 request/response schema, no documentation beyond a landing page catalog, and the specific /api/v1/inbox/15 endpoint is not listed in the public catalog — its actual functionality is unknown.
Warnings
- —The endpoint /api/v1/inbox/15 does not appear in the site's public API catalog; its purpose is undocumented.
- —No OpenAPI spec, no request/response schema, and no usage examples are available.
- —The /api, /pricing, and /README pages only show a wallet-connect prompt with no documentation content.
- —Actual functionality behind this endpoint cannot be verified from available materials.
Citations
- —All endpoints are priced at $0.02 per request with no API keys, no rate limits, and instant access on the Base network.https://lowpaymentfee.com
- —The x402 challenge for /api/v1/inbox/15 advertises maxAmountRequired of 20000 base units of USDC (asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Base.https://lowpaymentfee.com/api/v1/inbox/15
- —Available API categories include Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructure.https://lowpaymentfee.com