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 encrypts the connection and proves the site controls the domain 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 and forms stop converting. 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 two-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 7 days (urgent).
| Result | What it means |
|---|---|
| Valid and trusted | The certificate is trusted, covers this domain, is not expired, and has more than 30 days left. |
| Expiring soon | The certificate is still valid but expires in 30 days or less. Renew before it lapses. |
| Action needed | The certificate is expired, not trusted, does not cover this domain, or lapses in 7 days or fewer. 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 real TLS handshake against your host, not a lookup of a public certificate database. A recent result for the same domain is reused for up to 30 minutes, and the card always shows when the reading was measured.
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 tool, 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 7 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 counts down SSL and domain expiry on every site you add, and expiry rules you write once at agency level, one for SSL and one for domain, tell you before any of them lapses. That runs alongside uptime checks every minute on the homepage, plus daily Lighthouse and visual checks that roll into a branded report your client actually reads.
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- ✓ 2-minute setup. Add a URL. SiteLetter auto-discovers pages, starts monitoring, schedules reports. You pick your alert rules and confirm each client address once.
- ✓ No scripts to install. SiteLetter monitors from the outside, like a real visitor.
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