SSL certificate checker
Every checker gives you the expiry date. This one also tells you whether the server sends its intermediate certificate, which is the reason a site works on your laptop and fails on a phone.
5 checks a minute and 20 an hour from one address, and 3 a minute for any given domain, across both free tools. Enough for a person, not enough to hammer a site through us.
What a certificate checker answers, and what this one also answers
| The question you actually have | A usual online checker | This page |
|---|---|---|
| When does it expire? | Yes, and well | Yes |
| Does the server send the intermediate certificate? | Rarely, and rarely in plain words | Advantage: UptimeEZ. Yes, and what to do about it |
| Does it cover the exact name I typed? | Sometimes | Advantage: UptimeEZ. Yes, wildcards included |
| Is it the certificate, or has the domain expired? | Not answered | Advantage: UptimeEZ. Both dates, side by side |
| Can I test a mail server or a custom port? | Advantage: the usual tools. Often, on any port | Ports 80 and 443 only |
| Will it warn me when the date approaches? | Advantage: the usual tools. Some send an email | Not from this page. That needs monitoring |
Two rows go the other way, and they are the honest ones: a fixed pair of ports and no alerting are real limits of a one-off check.
The certificate reading, the expiry thresholds and the wording of every diagnosis are in the engine source, which is public and MIT: src/Check/Ssl.php for the two-pass read, src/Check/DomainExpiry.php for the domain date, src/Diagnose.php for what it tells you to do about each one.
The last row has a page of its own: watching every certificate in a client portfolio. If what brought you here was a site behaving strangely rather than a date, the same treatment applied to the page itself reads the HTML, the stylesheets and the noindex as well.
And if you would rather see how the seven usual tools handle all this: the whole comparison in one table, or what separates monitoring tools and how to test one.
Questions people actually ask
Why does my certificate work in Chrome but fail on Android?
Almost always because the server sends only its own certificate and not the intermediate that links it to a root authority. Desktop browsers repair this silently: they fetch the missing intermediate, or they already have it cached from another site. Android, Java, curl and most API clients do not repair it, so for them the certificate cannot be verified. The fix is to redeploy the certificate with the intermediate chain concatenated after it.
How many days before expiry should I worry?
Fifteen is the threshold this tool warns at, and the reason is mechanical rather than cautious: a certificate that renews automatically has had several attempts by then, so anything still unrenewed at fifteen days is a renewal that is not happening. Warning at thirty produces noise nobody reads, and warning at three leaves no time for a certificate authority to answer.
Does a valid certificate mean the site is fine?
No. A certificate can be perfectly valid for a name your visitors do not use, which is what happens when a wildcard covers www.example.com but the site also answers on example.com. It can also be valid on a domain that expires next month, which looks exactly like a broken certificate and is repaired in a completely different place.
Can I check a certificate on a port other than 443?
Not from this page, and that is deliberate. A public tool that connects to any port you name is a port scanner, and it is our IP address that appears in the logs of whoever you scan. Ports 80 and 443 are the only two this tool will touch.
Does checking once protect me from the certificate expiring?
It cannot. You read a number today, and the day it reaches zero nothing on this page will have told you, because you will not have thought to come back. That gap is the whole difference between a checker and monitoring, and it is why this page says so instead of pretending otherwise.
You will not think to come back on the day it matters
Nobody does. Certificate outages happen to people who checked once, saw ninety days, and moved on. Monitoring is the version where the number is watched for you and the message arrives while there is still time to act.