Check a Domain's SSL, WHOIS, and Security Headers for Free — Then Keep Watching

Before you sign off on a website, a domain purchase, or a handover, you want a fast health check. These three free tools give you that in about a minute — no signup — and each one points at a permanent monitor you can switch on afterwards.

1. SSL Certificate Checker

The free SSL checker shows a certificate's issuer, validity dates, days remaining, and chain status. Run it when:

• Someone says "the site has an SSL error" and you want the facts fast.
• You are auditing a domain before buying or taking it over.
• You want to check a renewed certificate actually deployed correctly.

The certificate you check today will expire months from now — and nothing will email you about it. The upgrade is an SSL certificate monitor, which tracks days remaining and alerts you weeks before expiry. It is one of the few monitors that prevents an outage rather than reports one.

2. WHOIS Lookup

The WHOIS lookup tool shows registration and expiry dates, registrar, and nameservers. Run it when you need to confirm who owns a domain or when a domain actually renews. The permanent version is a domain expiry monitor (alerts long before the domain lapses) plus a WHOIS change monitor that alerts if the registrar, nameservers, or status change — an early warning for a hijack attempt. For most owners, "the domain quietly expired" is the most preventable disaster there is.

3. Security Headers Checker

The security headers tool grades a site's CSP, HSTS, X-Frame-Options, and friends from A to F. Run it as a quick audit — you will be surprised how many otherwise modern sites score poorly. Headers drift over time (a plugin or CDN change drops HSTS, a caching layer strips CSP), so the permanent version is a security headers monitor that grades on a schedule and alerts on regression.

Why the Checker Becomes a Monitor

A checker answers "right now." Each of these three things changes slowly and silently — which is exactly why they are better monitored than checked:

• SSL and domain expiry move toward a deadline you do not want to miss.
• Security headers and WHOIS records can change without anyone noticing.
• None of them cause a visible outage until the moment they do.

SSL certificate and domain expiry monitors are included in Monitorion's free plan, with security headers too. Add them today and you will never have to remember to re-check.

Run the checks now at monitorion.com/free-tools — then create a free account and turn the results into monitors.