x402-gated API key endpoint on Base, paying $0.02 in USDC per request.
What it does
This endpoint at lowpaymentfee.com provides "Premium API Access" via the x402 payment protocol. It is one of many endpoints on the lowpaymentfee.com platform, which offers a broad catalog of pay-per-call APIs spanning data & analytics, 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/apikeys/21` is described only as "Premium API Access" with no further documentation on what it returns or what input it expects. The x402 challenge confirms it is live, accepts POST requests, and requires an exact payment of 20,000 base units of USDC (0x8335…2913 on Base), which equals $0.02 given USDC's 6 decimals. Payment is sent to address 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3 with a 300-second timeout.
Documentation on the site is extremely sparse — the /docs, /api, /pricing, and /README pages all render only a "Connect wallet" prompt with no additional content. There is no OpenAPI spec, no request/response schema, and no examples available. The purpose of this particular endpoint (API key generation? API key retrieval?) is unclear from the available material.
Capabilities
Use cases
- —Purchasing or retrieving an API key via a single micropayment
- —Agent-driven access to gated API resources without pre-registration
- —Programmatic pay-per-use API key provisioning
Fit
Best for
- —Agents needing instant API access without signup or subscriptions
- —Developers experimenting with x402 payment-gated endpoints
- —Micropayment-based API consumption on Base
Not for
- —Users who need detailed API documentation or schemas before purchasing
- —High-volume use cases where per-request pricing may add up
- —Anyone requiring non-crypto payment methods
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/apikeys/21 \
-H "X-PAYMENT: <x402-payment-token>" \
-H "Content-Type: application/json"Endpoint
Quality
The endpoint is live and returns a valid x402 challenge, but there is zero documentation on what this endpoint actually does, what inputs it accepts, or what it returns. No OpenAPI spec, no examples, and all doc pages are empty. The listing is effectively a stub.
Warnings
- —No documentation available — /docs, /api, /pricing, and /README pages all show only 'Connect wallet' with no content.
- —The purpose of /api/v1/apikeys/21 is unclear: it could generate, retrieve, or validate an API key, but nothing specifies this.
- —No request or response schema is provided anywhere.
- —No OpenAPI or machine-readable spec found.
Citations
- —The endpoint returns a 402 x402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/apikeys/21
- —All endpoints on the platform are priced at $0.02 per request with no minimums or commitmentshttps://lowpaymentfee.com
- —The platform offers APIs across data & analytics, AI & ML, finance & Web3, and infrastructure categorieshttps://lowpaymentfee.com
- —USDC asset address is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base networkhttps://lowpaymentfee.com/api/v1/apikeys/21