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 suite of 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.
The specific endpoint `/api/v1/keys/9` is listed as "Premium API Access" and its x402 challenge advertises a maxAmountRequired of 20,000 base units of USDC (0x8335…2913 on Base), which equals $0.02 given USDC's 6 decimals. Payment is made via the x402 exact scheme — no API keys, subscriptions, or rate limits are required. The platform emphasizes a simple pay-per-use model with instant access.
Documentation beyond the landing page is sparse: the /api, /pricing, and /README routes all return only a "Connect wallet" prompt with no additional technical detail. No OpenAPI spec, request/response schemas, or usage examples were found. The exact functionality behind the `/api/v1/keys/9` "Premium API Access" endpoint is unclear — it may serve as an API key provisioning or access-grant mechanism, but this is not documented.
Capabilities
Use cases
- —Accessing AI inference endpoints (sentiment, summarization, classification, embeddings) on a per-call basis without subscriptions
- —Fetching real-time financial data such as token quotes, exchange rates, and gas estimates
- —Running utility operations like geocoding, data validation, and format conversion with micropayments
- —Provisioning or obtaining premium API access keys via a single USDC payment
Fit
Best for
- —Developers who want pay-per-use API access without managing API keys or subscriptions
- —Agents and bots that can settle payments programmatically via x402 on Base
- —Projects needing low-cost, low-friction access to a variety of common API services
Not for
- —Users who need detailed API documentation, schemas, or guaranteed SLAs before integrating
- —High-volume production workloads that would benefit from bulk pricing or rate-limited tiers
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/keys/9 \
-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 it accepts USDC on Base at $0.02. However, there is no OpenAPI spec, no request/response schema, no usage examples, and the specific purpose of /api/v1/keys/9 ('Premium API Access') is undocumented. The /api, /pricing, and /README pages are all empty beyond a wallet-connect prompt.
Warnings
- —No OpenAPI or schema documentation available for any endpoint
- —The exact functionality of /api/v1/keys/9 ('Premium API Access') is unclear — it may be a key provisioning endpoint or something else entirely
- —All documentation pages (/api, /pricing, /README) return only a 'Connect wallet' prompt with no technical content
- —No request or response examples are available anywhere in the crawled material
Citations
- —The endpoint returns a 402 x402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/keys/9
- —USDC asset address is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base networkhttps://lowpaymentfee.com/api/v1/keys/9
- —All listed endpoints are priced at $0.02 per request with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —The platform offers endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com