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 offered by the lowpaymentfee.com platform, which hosts a variety of pay-per-call APIs spanning data & analytics, AI & machine learning, finance & Web3, and infrastructure utilities — all priced at $0.02 per request settled in USDC on the Base network.
The specific resource `/api/v1/apikeys/9` is listed under the title "Premium API Access." The x402 challenge confirms it is live, accepting POST requests, and requires an exact payment of 20,000 base units of USDC (0x8335…2913 on Base, 6 decimals → $0.02) per call. Payment is sent to address 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3 with a 300-second timeout. No API key or account registration is needed; access is granted purely through the x402 payment header.
Documentation is extremely sparse. The crawled /docs, /api, /pricing, and /README pages all returned only a "Connect wallet" prompt with no further content. There is no OpenAPI spec, no request/response schema, and no description of what this particular endpoint actually returns beyond its title. The broader site lists 16 endpoints across four categories, but none include detailed documentation. Prospective callers should be aware that the actual behavior of this endpoint is undocumented and must be discovered empirically.
Capabilities
Use cases
- —Acquiring API keys or premium access tokens via micropayment
- —Agent-driven programmatic access to gated resources without pre-registration
- —Demonstrating x402 payment protocol integration on Base
Fit
Best for
- —Developers experimenting with x402 payment-gated APIs
- —AI agents that need keyless, pay-per-call API access
- —Projects requiring low-friction micropayment API consumption on Base
Not for
- —Users who need detailed API documentation or guaranteed SLAs
- —High-volume use cases where $0.02/request adds up significantly
- —Anyone needing non-crypto payment rails
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/apikeys/9 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-header>"Endpoint
Quality
The endpoint is live and returns a valid x402 challenge with clear pricing. However, there is no OpenAPI spec, no request/response schema, no documentation beyond a title, and the crawled doc pages are empty. The actual functionality of this specific endpoint is unknown beyond its name.
Warnings
- —No documentation available — /docs, /api, /pricing, and /README pages all render only 'Connect wallet' with no content.
- —No request or response schema provided; callers must discover behavior empirically.
- —The purpose of '/api/v1/apikeys/9' is unclear — 'Premium API Access' is the only description available.
- —No OpenAPI or ai-plugin manifest found.
Citations
- —The endpoint returns a valid x402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/apikeys/9
- —All endpoints on the platform are priced at $0.02 per request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —The platform offers 16 endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com
- —Documentation pages (/docs, /api, /pricing, /README) contain only 'Connect wallet' with no substantive contenthttps://lowpaymentfee.com/docs