Website Uptime Checker

Instantly check if any website is online, its HTTP status code, and response time from our global servers.

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What This Uptime Checker Verifies

HTTP Status Code
Sends a live request to your domain and reports the exact HTTP status code returned — 200 OK, 404 Not Found, 500 Server Error, and more.
Response Time
Measures how quickly your server responds, in milliseconds, and grades it Excellent, Good, Fair, or Slow.
Protocol (HTTPS/HTTP)
Detects whether your site was reached over encrypted HTTPS or plain HTTP, falling back automatically if HTTPS is unavailable.
Redirects
Flags when your URL redirects to a different final destination than the one you entered.
Server Header
Shows the Server header and Content-Type returned by your infrastructure, when available.
Downtime Detection
Flags 4xx and 5xx responses or unreachable connections so you know immediately when something is wrong.

Frequently Asked Questions

How does the uptime checker work?

Our checker sends an HTTP HEAD request to your domain over HTTPS (falling back to HTTP) and measures the response time. It reports the HTTP status code, whether the server is reachable, and how quickly it responds. A status code below 500 is considered online.

What does a 200 OK response mean?

HTTP 200 OK means the server received the request and returned a successful response. Your site is online and reachable. 3xx codes indicate redirects, 4xx indicate client errors (like 404 Not Found), and 5xx indicate server errors.

What is a good response time for a website?

Under 300ms is excellent, 300-800ms is good, 800-2000ms is fair, and over 2000ms is slow. Slow response times increase bounce rates significantly — studies show 53% of mobile users abandon pages that take over 3 seconds to load.

How is this different from continuous monitoring?

This tool performs a one-time check from our server. For continuous 24/7 monitoring with alerts when your site goes down, sign up for CertNotify monitoring which checks your site every few minutes and sends email or WhatsApp alerts instantly on downtime.

Why does my site show as unreachable even though it loads in my browser?

Your site may block server-to-server HEAD requests, use IP-based access restrictions, require JavaScript to load (SPAs), or be behind a CDN/WAF that blocks automated requests. Try checking a specific resource URL or ensure your site accepts requests from external servers.

Get Alerted the Moment You Go Down

CertNotify monitors your uptime around the clock and sends instant alerts via email or WhatsApp the moment your site goes down.

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