Free website diagnostic tools
Check whether a website is down, inspect HTTP status codes and redirects, verify SSL certificates and look up DNS records. No account required.
Website Status Checker
Free website status checker: check if a website is online or down for everyone or just you, with HTTP status, response time and the failure reason.
Open toolHTTP Status Code Checker
See the HTTP status code a URL returns, every redirect along the way and the most important response headers.
Open toolWebsite Response Time Checker
Test your website response time for free. See time to first byte and how long DNS, connection, SSL and the server each take, measured three times.
Open toolSSL Certificate Checker
Check a website's SSL/TLS certificate: whether it is trusted, when it expires, who issued it and which domains it covers.
Open toolDNS Lookup
Look up the DNS records of a domain: A, AAAA, CNAME, MX, NS and TXT. Useful for diagnosing website and email problems.
Open toolWhen to use each tool
When a website stops working, the cause is usually in one of a few places: the domain name doesn't resolve, the secure connection fails, the server doesn't answer, or the application returns an error. Each tool looks at one of these layers.
- DNS Lookup answers "where does this domain point?" Use it after changing hosting or DNS providers.
- SSL Certificate Checker answers "is the certificate valid, and when does it expire?"
- Website Status Checker answers "does the website respond right now, and how fast?"
- Website Response Time Checker answers "how fast does the server respond, and which step is slow?"
- HTTP Status Code Checker answers "what exactly does the server return, and where does it redirect?"
For a deeper walkthrough, read How to Check If a Website Is Online or Down. To run these checks continuously instead of by hand, see our guide to uptime monitoring.
All tools run from our server and refuse to contact private or internal network addresses. To prevent abuse, the number of checks per visitor is limited.
Want these checks to run automatically?
Monitor up to 5 websites every 5 minutes for free and get an email when something breaks.