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URL Uptime Checker
x402
URL Uptime Checker is a paid API for AI agents from url-uptime-checker.underscoredone.com, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-13).
Checks whether a given URL is currently online and reachable, returning status code, response time, and redirect details.
Price / call$0.01
Success—
StatusUnknown
How this service works
Checks whether a website or web address is currently reachable and reports how fast it responded.
Output
A JSON object containing whether the URL is up (boolean), the HTTP status code, response time in milliseconds, the final URL after any redirects, whether a redirect occurred, and the timestamp the check was performed.
Example use cases
Validate links before sending
“Before we email our customer list, can you quickly check if all the links in our newsletter are live and accessible? Just need to know which ones are broken so we can fix them.”
Monitor deployment health check
“We just pushed an update to production — can you verify that our main app URL is responding normally and check what the response time looks like from outside our network?”
Catch redirect loops fast
“Our marketing team says one of our old campaign links isn't working right. Can you check where it's actually redirecting to and tell me if it's going in circles or resolving properly?”
Technical details
Endpoint
POSThttps://url-uptime-checker.underscoredone.com/checkWhen to prefer
Use this endpoint when you need a quick, real-time check of whether a specific URL is reachable from an external vantage point. Ideal for pre-flight checks before scraping, link validation, lightweight health monitoring, or confirming a deployment is live. Prefer this over full monitoring platforms when you only need a single on-demand check rather than continuous polling.
Side effects
- URL is unreachable or DNS fails — 'up' is false with an error message
- Invalid or malformed URL input — API may return an error or treat as down
- Target server responds very slowly causing a timeout — may be reported as down
- URL requires authentication — may return 401/403 but still reported as 'up' depending on status logic
- Network issues on the checker's side — false negatives possible
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| url | string | The full web address to check, including http:// or https:// at the start. |
| method | string | Which kind of request to send: 'GET' to fetch the page or 'HEAD' to just check reachability faster. Defaults to 'GET'. |
| follow_redirects | boolean | Whether to follow redirects to their final destination before reporting the result. Defaults to true. |
Output
Schema · Response
{
"type": "json",
"example": {
"up": true,
"url": "https://example.com",
"error": "",
"final_url": "https://example.com/",
"checked_at": "2026-07-23T04:12:09Z",
"redirected": false,
"api_version": "1.0.0",
"status_code": 200,
"response_time_ms": 184
}
}Tags
x402
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