x402-gated premium API endpoint on Base, pay-per-request with USDC.
What it does
This endpoint at `/api/endpoint-4` is part of the lowpaymentfee.com platform, which offers a collection of x402-protocol pay-per-request APIs spanning data & analytics, AI/ML inference, finance & Web3 data, and infrastructure utilities. The endpoint is labeled "Premium API Access" and accepts POST requests, returning application/json responses. Payment is handled via the x402 exact scheme on the Base network using USDC (asset 0x8335…2913), with a maximum amount of 20,000 units (likely 0.02 USDC given the 6-decimal USDC standard, consistent with the site's advertised $0.02/request pricing).
The platform advertises no API keys, no rate limits, and instant access — payment is the only gate. However, the specific functionality behind `/api/endpoint-4` is not documented on the site's landing page, which lists endpoints under `/api/v1/` and `/api/v2/` paths but does not mention `/api/endpoint-4`. The docs, pricing, and README pages returned only a "Connect wallet" prompt with no substantive content. Without documentation or an output schema describing what this endpoint actually does, its concrete capabilities remain unknown. It is live and responds with a valid 402 challenge, but prospective callers should be aware that the purpose and expected input/output format are undocumented.
Capabilities
Use cases
- —Programmatic access to an undocumented premium API service via x402 micropayment
- —Agent-driven pay-per-request API consumption without API keys
- —Demonstrating x402 payment protocol integration on the Base network
Fit
Best for
- —Developers experimenting with x402 payment-gated APIs
- —Agents that can handle x402 challenges and USDC payments on Base
- —Users who want keyless, pay-as-you-go API access
Not for
- —Anyone needing documented input/output contracts before calling
- —Use cases requiring guaranteed SLAs or support
- —Users without access to USDC on the Base network
Quick start
curl -X POST https://lowpaymentfee.com/api/endpoint-4
# Returns 402 with X-PAYMENT challenge; attach a valid x402 payment header to proceed.Example
Response
{
"error": "X-PAYMENT header is required",
"accepts": [
{
"asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
"extra": {
"name": "USD Coin",
"version": "2"
},
"payTo": "0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3",
"scheme": "exact",
"network": "base",
"mimeType": "application/json",
"resource": "https://lowpaymentfee.com/api/endpoint-4",
"description": "Premium API Access",
"maxAmountRequired": "20000",
"maxTimeoutSeconds": 300
}
],
"x402Version": 1
}Endpoint
Quality
The endpoint is live and returns a valid 402 challenge, but the specific functionality of /api/endpoint-4 is completely undocumented. The site's landing page lists many other endpoints but not this one. Docs, pricing, and README pages are empty beyond a wallet-connect prompt. No input/output schema, no examples, and no description of what the endpoint actually does.
Warnings
- —The endpoint /api/endpoint-4 is not listed among the documented APIs on the site's landing page — its purpose is unknown.
- —All documentation pages (docs, pricing, README) returned only 'Connect wallet' with no substantive content.
- —No input schema or output schema is provided beyond the generic x402 challenge metadata.
- —The actual functionality behind this endpoint cannot be verified without making a paid request.
Citations
- —The site advertises $0.02/request pricing with no API keys, no rate limits, and instant access on the Base network.https://lowpaymentfee.com
- —The 402 challenge specifies USDC on Base with maxAmountRequired of 20000 and payTo address 0x1A2B…85F3.https://lowpaymentfee.com/api/endpoint-4
- —The site lists endpoints under /api/v1/ and /api/v2/ paths but does not list /api/endpoint-4.https://lowpaymentfee.com