Free SSL certificate checker
An SSL certificate checker that reads the live certificate off the TLS handshake. Enter a domain to see its issuer, expiry date, the days remaining, and whether the chain and hostname actually validate — not just whether a padlock shows.
What this checks, and how
This tool connects to the domain the same way a browser does, completes the TLS handshake, and reads the certificate the server actually presents. That is different from a database lookup: you are seeing the live certificate this minute, including a renewal that went out an hour ago or one that quietly failed last week. It then answers the three questions a padlock rolls into one — is it in date, is the chain trusted, and does the hostname match — and reports each separately so you can tell which one is wrong.
Why expiry is the one to watch
An expired certificate is the most common way HTTPS breaks, and it is entirely avoidable. Certificates are short-lived by design now, and renewal is usually automated — which is exactly why a failure goes unnoticed, since nobody is watching a process that normally runs itself. When it lapses, every visitor hits a full-page browser warning and most leave immediately. The days-remaining figure here is the number to keep an eye on; if it is under thirty, a renewal should already be scheduled.
HTTPS and search
HTTPS is a genuine ranking signal, but a small one — the real SEO cost of a certificate problem is indirect. A page a crawler cannot fetch over a trusted connection is a page that does not get indexed, and a security warning drives the bounce rate that erodes the behavioral signals search engines do watch. If a page has dropped out of results and its certificate is broken, fix the certificate before looking anywhere else. Our guide on why a website is not showing up on Google covers the other causes in order.
Where this fits
A valid certificate is one layer of a healthy site. The same host has DNS records that need to resolve, response headers worth hardening and a page that has to load quickly — the DNS lookup checker and the HTTP header checker cover the two next to this one. To see all of it scored together, the free website checker runs every check we have in about thirty seconds, and what counts as a good score explains how to read the result.
SSL certificate questions
- What does an SSL certificate checker do?
- An SSL certificate checker opens a live TLS connection to a domain and reads the certificate the server presents. It reports who issued the certificate, the exact dates it is valid between, how many days remain before it expires, the other hostnames it covers, and — the part that matters most — whether the certificate chain is trusted and the hostname actually matches. This tool does all of that in one lookup, with no signup.
- How do I know if my SSL certificate is valid?
- A certificate is valid when three things are true at once: it is inside its date range, the chain links up to a trusted root authority, and the hostname you visited is covered by the certificate. A padlock in the browser only confirms the first and last for the exact page you are on — it does not tell you how many days are left or whether an intermediate certificate is missing. This checker separates the three so you can see which one is failing.
- When does my SSL certificate expire, and how often should I renew it?
- Most certificates today are issued for a maximum of about 13 months, and free ones from Let's Encrypt last 90 days. The safe practice is automatic renewal well before expiry — 30 days is a common buffer. This tool shows the exact expiry date and the number of days remaining, and turns negative once a certificate has lapsed, so you can catch a renewal that silently failed before visitors see a full-page security warning.
- What does a certificate name mismatch mean?
- A name mismatch means the certificate is valid and trusted, but it does not list the hostname you visited among the names it covers. It commonly happens when a certificate is issued for example.com but not www.example.com, or when a server block is misconfigured to serve the wrong site's certificate. Browsers treat it as a hard error and block the page, so it is worth catching directly — this tool checks the hostname against both the subject and the Subject Alternative Names.
- Does HTTPS affect SEO or Google ranking?
- Yes, but modestly. Google has used HTTPS as a lightweight ranking signal since 2014, and Chrome marks plain HTTP pages as 'Not secure', which costs trust and clicks. A broken or expired certificate is the bigger SEO risk: it blocks the page entirely, so crawlers cannot fetch it and users bounce at the warning screen. Keeping the certificate valid is table stakes rather than an optimization.
- What is a certificate chain and why does a missing intermediate break it?
- A certificate chain links your certificate to a root authority every browser already trusts, usually through one or two intermediate certificates in between. If the server sends your certificate but forgets to send the intermediates, some browsers can rebuild the chain from cache and others cannot — which produces the maddening 'works in Chrome, fails on this phone' bug. A chain check catches the missing intermediate that a single-browser test hides.
- Is a self-signed certificate a problem?
- For a public website, yes. A self-signed certificate encrypts traffic but is not vouched for by any trusted authority, so every browser shows a full-page warning. They are fine on internal tools and local development, but a public page needs a certificate from a recognized authority — free ones are available and automate cleanly. This tool flags a self-signed or untrusted certificate distinctly from an expired one, because the fix is different.
- Why does my site still say 'Not secure' after installing an SSL certificate?
- The usual cause is mixed content — the page loads over HTTPS but still pulls an image, script or stylesheet over plain HTTP, which downgrades the whole page. Update those references to HTTPS, and make sure every URL redirects to the secure version, then reload with the cache cleared.
- How do I check the SSL certificate of a website?
- Enter the domain above and this tool reports whether the certificate is valid, who issued it, when it expires and whether the chain is complete. In a browser you can also click the padlock in the address bar to view the same certificate details.
- What is the difference between SSL and TLS?
- TLS is the modern successor to SSL, and every current secure certificate actually uses TLS even though the industry still calls them SSL certificates out of habit. The name persists for familiarity, but the protocol doing the encryption today is TLS.
- Do I need an SSL certificate for a small website?
- Yes — every site needs HTTPS regardless of size, because browsers now mark plain HTTP pages as 'Not secure' and Google treats HTTPS as a ranking signal. A free certificate from Let's Encrypt covers most small sites at no cost, so there is no reason to run without one.
- What happens when an SSL certificate expires?
- When a certificate expires, browsers show a full-page security warning that most visitors will not click past, effectively taking the site offline for them. Renewal is the only fix, so set up automatic renewal — most free certificates last 90 days precisely to encourage it.
- What is a wildcard SSL certificate?
- A wildcard certificate secures a domain and all of its first-level subdomains with a single certificate, so one issued for *.example.com covers www, blog and shop subdomains alike. It is convenient for sites with many subdomains, but it does not cover deeper levels or a different root domain.