Days until expiry
The exact expiry date and how many days remain — the number one cause of preventable SSL-related outages.
Free SSL Certificate Checker
Enter a domain to instantly check its SSL/TLS certificate: days until expiry, issuer, valid dates, TLS protocol, and whether the chain is trusted.
Check an SSL certificate
Enter a domain (for example, northduty.com). NorthDuty connects over HTTPS and reports the live certificate details.
Free check. No signup. Results are not published or indexed.
How NorthDuty SSL monitoring works
Enter a domain (for example, northduty.com). NorthDuty connects over HTTPS and reports the live certificate details. Recurring checks are configured inside the NorthDuty app.
What this SSL checker reports
A single check returns the certificate facts that most often cause outages and browser warnings.
Issuer and subject
Which certificate authority issued the certificate and which hostnames it covers, so you can confirm it matches the domain.
Valid-from and valid-to dates
The certificate's full validity window, including not-before dates that can break a freshly rotated certificate.
TLS protocol and trust
The negotiated TLS protocol version and whether the presented chain is trusted by standard root stores.
Why check SSL certificates
Expired or misconfigured certificates take sites offline in a way uptime pings often miss until customers complain.
- Catch certificates that are close to expiry before browsers show a warning
- Confirm a renewed or rotated certificate actually deployed correctly
- Verify the certificate covers the exact hostname your customers visit
- Spot weak or outdated TLS protocol versions
- Check certificates across staging and production domains in seconds
How the SSL checker works
No signup, no agent — just a live HTTPS connection to the domain you enter.
1
Enter a domain
Type any public domain or hostname. NorthDuty resolves it and opens an HTTPS connection on port 443.
2
We read the live certificate
The presented certificate is parsed for issuer, subject, validity dates, and the negotiated TLS protocol.
3
You get a plain-language result
Days-to-expiry, trust status, and the key dates are shown immediately — no report snapshot is stored.
4
Turn it into continuous monitoring
Add the domain to NorthDuty and get alerted automatically before the certificate expires, on every renewal.
Go Beyond One-Off Checks
Use the tool preview for a quick answer, then move into recurring monitoring for your most important pages and journeys.
Feature
SSL Certificate Monitoring
Monitor SSL certificates with NorthDuty website health checks so validity, trust, and expiry issues are visible before visitors are blocked.
Explore SSL Certificate MonitoringFeature
Uptime Monitoring
Monitor uptime every 5 minutes by default with HTTP, SSL, DNS, blank-page detection, broken resources, JavaScript errors, and API call tracking.
Explore Uptime MonitoringArticle
SSL Certificate Monitoring
Learn how SSL certificate monitoring works inside NorthDuty website health checks.
Read SSL Certificate MonitoringPricing
Pricing
NorthDuty pricing for website monitoring: Free, $29 Starter, $79 Pro, $199 Business, and $499 Enterprise plans.
Compare pricing plansFrequently Asked Questions
Answers about this diagnostic preview and when to move into recurring monitoring.
Is this SSL checker free?
Yes. The SSL certificate checker is completely free and requires no signup. Enter a domain and you get the live certificate details immediately.
What does the checker actually connect to?
It opens a standard HTTPS (TLS) connection to the domain you enter on port 443 and reads the certificate the server presents — the same certificate a browser would receive.
Do you store the domains I check?
NorthDuty does not create a stored or indexed public report. If you copy a share link, the domain remains in that URL and opening it reruns a live check.
How is this different from monitoring SSL with NorthDuty?
This tool answers a single point-in-time question. NorthDuty checks SSL continuously as part of every website health check and alerts you in advance of expiry, so a missed renewal never becomes an outage.
Call To Action
Start monitoring your website with NorthDuty today.
A one-off SSL check is useful, but certificates expire on a schedule. Let NorthDuty watch your certificates continuously and alert you before they lapse.
Start on the free plan — add your base URL and monitoring starts in minutes.