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 layer underneath HTTPS: the same HTTP requests, carried over an encrypted connection, which is what the padlock your browser shows in the address bar refers to. Every site that handles a login, a form, a payment, or just wants browsers to trust it, presents a certificate. The certificate proves the site controls the domain it claims to be, and the browser uses it to set up the encrypted connection.
That certificate has an expiry date. When it lapses, browsers stop showing the padlock and put a full-screen security warning in front of the page instead, so the warning is what loads ahead of the content, the form and the checkout. Whether anything reminds you before that date arrives depends on your certificate issuer and your host, so the safe assumption is that the date is yours to watch.
For an agency, a lapsed certificate on a client's site is an avoidable emergency: the expiry date is written into the certificate from the day it is issued, so it is one of the few problems you can be early for. A 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 results, and the red one names the specific problem: expired, wrong domain, or not trusted. 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. Live checks are capped at 10 per domain every 10 minutes, and that cap is shared by everyone checking the same domain rather than counted per visitor. A recent result for the same domain is served from cache and does not draw on it. Hit the cap and the tool says so and asks you to try again shortly.
They describe the same padlock from different angles. TLS is the current encryption protocol and SSL is the older protocol it replaced, whose name stuck in everyday use. HTTPS is plain HTTP running over that encrypted TLS connection. If "check my SSL" is what you came here to do, the part this tool answers is the certificate: whether it is valid, who issued it, and how many days it has left.
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. Automatic renewal is a scheduled job like any other: it can stop running, lose the validation it depends on, or fail against a DNS record that moved, and nothing about the site looks different until the certificate lapses. So "it should renew itself" is worth confirming rather than assuming on a site you are responsible for. A certificate that lapses puts a full-page browser security warning in front of every visitor, 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 checks SSL and domain expiry daily on every site you add and counts down to the expiry date, 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 built to forward to your client.
Still have questions? Get in touch.
You set up care-plan reporting once.
After that it runs without you.
SiteLetter is the kind of tool you forget you're using, until your client thanks you for the report you didn't write.
- ✓ Just add a domain. SiteLetter auto-discovers pages, starts monitoring, schedules reports. You pick your alert rules and who gets each report.
- ✓ No scripts to install. SiteLetter monitors from the outside, like a real visitor.
- ✓ Nothing recurring. No subscription, no contract. You buy credits when you want them and each site spends its own.