Pay-per-call API platform on Base (USDC) covering data, AI, finance, and utility endpoints at $0.02/request.
What it does
lowpaymentfee.com is an x402-enabled API platform that offers a broad catalog of pay-per-request endpoints settled in USDC on the Base network. The specific endpoint at `/api/v1/keys/55` 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 — callers include an X-PAYMENT header with a signed payment proof, and no traditional API keys or accounts are required.
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 endpoints are listed at the same $0.02 per request price point with no rate limits or minimum commitments.
However, the specific endpoint probed (`/api/v1/keys/55`) does not clearly map to any of the documented API categories, and its actual functionality is not described beyond the generic "Premium API Access" label. There is no OpenAPI schema, no request/response examples, and the crawled documentation pages (pricing, README, /api) returned only a "Connect wallet" prompt with no additional content. The endpoint is confirmed live (returns a valid 402 challenge), but what it actually returns upon successful payment is unknown.
Capabilities
Use cases
- —Accessing pay-per-call data and analytics endpoints without creating an account
- —Running AI inference tasks (sentiment, summarization, classification, embeddings) with per-request USDC payments
- —Fetching financial data such as token quotes, exchange rates, and gas estimates via micropayments
- —Using utility services like geocoding and validation on a pay-as-you-go basis
Fit
Best for
- —Developers who want instant API access without signup or API key management
- —Agents and bots that can settle payments programmatically via x402 on Base
- —Users who prefer per-request pricing over subscription models
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/keys/55 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <signed-x402-payment-proof>"Endpoint
Quality
The endpoint is confirmed live with a valid x402 402 challenge, but there is no OpenAPI schema, no request/response examples, and the actual functionality of /api/v1/keys/55 is undocumented. The crawled pages beyond the homepage returned no useful content. The listing is effectively a stub.
Warnings
- —The endpoint path /api/v1/keys/55 does not correspond to any documented API category on the site — its actual functionality is unknown.
- —No OpenAPI spec, request schema, or response schema is available.
- —Documentation pages (/pricing, /README, /api) returned only 'Connect wallet' with no content.
- —Without knowing what the endpoint returns, callers risk paying $0.02 for an unknown response.
Citations
- —The endpoint returns a valid x402 402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/keys/55
- —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 in Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com
- —USDC asset address is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/keys/55