Why we built this
An expired SSL certificate takes a site offline faster than almost any other kind of outage. Browsers show scary red warnings, search engines drop you from rankings, and customer trust evaporates in minutes. And yet the most common SSL checker tools are slow, covered in ads, or require you to sign up before they'll tell you something as simple as "this certificate expires next Tuesday."
We built SSL Checker so we could stop reaching for openssl on the command line every time we needed to verify a certificate. It connects to the domain, reads the full certificate chain, checks the expiry date, validates the trust path, and flags common issues like missing intermediate certificates or mismatched hostnames — all in a single view, in seconds, with no signup and no hidden tiers.
Who's behind it
SSL Checker is part of ModusOp, a platform for operations, bookings, and client management built for small businesses and agencies. We build free developer tools like this one because we use them ourselves when onboarding clients, troubleshooting outages, and doing quick sanity checks — and because tools that are useful should be free whenever they can be.
The tool is built and maintained by JWWD, an Australian web development studio that handles the technical side of ModusOp. We've been shipping production web software since the early 2000s and we've watched more than one site go down over a forgotten cert renewal. This tool exists so that doesn't have to happen to you. To learn more about the wider platform, visit the main ModusOp site.
Our other free tools
SSL Checker is one of several free tools we run. If this one was useful, you might like the others — all of them free, no signup, and designed to give clear answers fast:
- DMARC Dashboard — inspect a domain's SPF, DKIM, and DMARC email authentication records.
- Meta Tag Checker — grade any page's SEO meta tags, Open Graph, Twitter Cards, headings, and image alt text.
- Site Speed Check — measure real-world page speed and get prioritised recommendations.
- Broken Link Finder — crawl any site and report broken internal and external links.
Get in touch
Got a question, a bug report, or a suggestion for a check we should add? Head to our contact page and send us a message — we read every one. To learn more about ModusOp itself, visit modusop.app.