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 provides a broad catalog of pay-per-request endpoints settled in USDC on the Base network. The specific endpoint at `/api/v1/keys/43` 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, accounts, or subscriptions are required; callers attach an X-PAYMENT header to each request.
The wider 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 listed endpoints share the same $0.02/request pricing with no rate limits or minimum commitments.
Important caveat: the specific endpoint `/api/v1/keys/43` is labeled only "Premium API Access" with no further documentation about what it returns or what input it expects. The site's docs, pricing, and README pages all resolve to a minimal "Connect wallet" prompt with no additional technical detail. There is no OpenAPI spec, no request/response examples, and no description of the data this particular endpoint provides. Treat this listing as a live but under-documented x402 endpoint.
Capabilities
Use cases
- —Agents that need on-demand API access without pre-registration or API keys
- —Programmatic access to utility/data endpoints with crypto micropayments
- —Testing x402 protocol integrations against a live endpoint
Fit
Best for
- —Developers experimenting with x402 payment protocol
- —Agents needing keyless, pay-as-you-go API access on Base
- —Low-volume callers who want no subscription commitments
Not for
- —Users who need detailed API documentation or OpenAPI specs before integrating
- —High-volume production workloads requiring SLAs or support
- —Users without USDC on the Base network
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/keys/43 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live (returns a valid 402 x402 challenge) and pricing is clear ($0.02 USDC on Base), but there is zero documentation on what this specific endpoint does, what inputs it accepts, or what it returns. No OpenAPI spec, no examples, and ancillary pages are empty. The listing is effectively a stub.
Warnings
- —No documentation exists for what /api/v1/keys/43 actually returns or accepts as input
- —No OpenAPI or schema available — request/response formats are unknown
- —Docs, pricing, and README pages all resolve to a minimal 'Connect wallet' page with no content
- —The endpoint name 'Premium API Access' is generic and does not describe functionality
Citations
- —The endpoint returns a 402 x402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/keys/43
- —All listed endpoints cost $0.02 per request with no API keys, no rate limits, and instant access on the Base networkhttps://lowpaymentfee.com
- —The platform offers endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com
- —USDC asset address is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/keys/43