SSL/HTTPS Checker
Enter any domain to check its certificate live: valid or not, who issued it, and how many days until it expires. Run it on your own site, a client's, or a prospect's before you pitch.
What SSL/HTTPS is, and why it matters
SSL, now more accurately called TLS, is the encryption that turns plain HTTP into HTTPS: the padlock your browser shows in the address bar. Every site that handles a login, a form, a payment, or just wants browsers to trust it, presents a certificate that proves the connection is encrypted and the domain is who it claims to be.
That certificate has an expiry date. When it lapses, browsers stop showing the padlock and start showing a full-page security warning instead. Visitors bounce, forms stop converting, and search engines take note. The failure is silent right up until the moment it is very loud, because nothing warns you the day before it expires unless you are watching for it.
For an agency, a lapsed certificate on a client's site is the kind of avoidable emergency that erodes trust in a retainer. A ten-second check like this one confirms the certificate is valid and tells you how much runway is left. Do it before a client call, before a launch, or the moment a client says "something looks wrong with my site".
How to read this result
The check returns one of four states. Here is what each one means and what to do about it. The two thresholds that matter are 30 days (warning) and 14 days (urgent).
| Result | What it means |
|---|---|
| Valid and secure | The certificate is trusted, not expired, and has comfortable time left (30+ days). |
| Expiring soon | The certificate is still valid but expires in under 30 days. Renew before it lapses. |
| Action needed | The certificate is expired, not trusted, or lapses in under 14 days. Visitors may see a security warning. |
| Couldn't verify | The host could not be reached or read to confirm its certificate. Neutral, not a failing grade. Try again shortly. |
About "Couldn't verify": a firewall, bot filter, or an unreachable host can stop an automated check from reading the certificate. That is not the same as an insecure site, so the result is neutral rather than a false red or green. If the padlock shows for you in a browser, the certificate is fine and something is just blocking the automated probe.
SSL/HTTPS checker FAQ
It connects to your domain over HTTPS and reads the SSL/TLS certificate the server presents. From that it tells you whether the certificate is currently valid, who issued it, when it expires, and how many days are left before it does. It is a live check, run the moment you press the button, not a cached lookup of a public database.
Yes, it is free and there is no signup. Type a domain, press Check, read the result. There is a light rate limit so one visitor cannot hammer the same host, but for normal use, checking a client site or a prospect site before a pitch, you will never hit it.
They describe the same padlock from different angles. TLS is the current encryption protocol (SSL was its older name, and the name stuck in everyday use). HTTPS is plain HTTP running over that encrypted TLS connection. When people say "check my SSL", they almost always mean "confirm my HTTPS certificate is valid and not about to expire", which is exactly what this tool does.
No. "Couldn't verify" means the check could not reach or read the host cleanly enough to confirm its certificate, so it does not guess. Common causes are a firewall or bot filter blocking the check, a host that timed out, or a domain that does not resolve. It is a neutral result, not a failing grade. Try again in a minute, and if it persists, open the site in a browser: if the padlock is there for you, the certificate is fine and something is just blocking automated checks.
Treat anything under 30 days as a warning and anything under 14 days as urgent. Most certificates auto-renew, but auto-renewal quietly fails often enough that "it should renew itself" is not a safe assumption for a site you are responsible for. A certificate that lapses shows every visitor a full-page browser security warning, so the goal is to renew well before the counter runs out, not on the last day.
Yes, that is what SiteLetter does. This one-off checker is handy for a quick look, but if you maintain client sites you do not want to remember to run it. SiteLetter watches SSL and domain expiry on every site you add and emails you before either lapses, alongside daily uptime, Lighthouse, and visual checks that roll into a branded report your client actually reads.
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