Certificate status
Waiting for check
[SSL certificate checker]
Check SSL certificates before browsers complain.
Inspect a domain's HTTPS certificate, issuer, expiry date, days remaining, SAN coverage, chain validity, TLS protocol, cipher, and SHA-256 fingerprint.
[TLS inspection]
See certificate health in one lookup.
Enter a domain or host:port. MarionetteOps connects over TLS, reads the certificate presented by the server, and summarizes whether it is valid, expiring soon, expired, trusted, and covering the requested host.
Expired certificates often look like downtime to customers
What this SSL certificate checker inspects
This free SSL checker connects to your domain over HTTPS and reads the certificate your server presents to visitors. It reports the certificate issuer, subject, expiration date, days remaining, subject alternative names, chain validation status, TLS protocol, cipher suite, serial number, and SHA-256 fingerprint. Use it as a quick launch checklist item before a production release, DNS cutover, CDN change, status page setup, or certificate renewal.
SSL and TLS certificate problems often feel like outages from the customer's point of view. A site can be online and still fail in every browser if the certificate expired, the hostname is not covered by the SAN list, an intermediate certificate is missing, or a proxy is serving an old certificate after a deployment.
Why SSL certificate expiry matters
Publicly trusted certificates have limited lifetimes, and renewal automation is not perfect. DNS validation can fail, ACME clients can break, file permissions can change, payment or account issues can interrupt a commercial certificate, and load balancers can continue serving an older certificate after the origin has already renewed. Checking the expiry date and days remaining gives teams a simple early warning before browsers, API clients, and customers reject the connection.
Manual SSL checks vs continuous monitoring
A manual SSL certificate checker is useful for spot checks, migrations, and incident triage. Production systems need continuous monitoring that checks certificates automatically and alerts before expiration. MarionetteOps pairs SSL checks with uptime monitors, DNS awareness, status pages, and alert routing so certificate drift is treated as reliability work rather than a calendar reminder.
SSL checker FAQ
How does this SSL checker work?
It connects to the domain over TLS, captures the certificate presented by the server, and extracts the issuer, subject, validity dates, SAN entries, TLS protocol, cipher, serial number, and fingerprint.
Can I check a certificate on a custom port?
Yes. Enter the host with a port, such as api.example.com:8443, and the checker will inspect the certificate served on that TLS port.
What happens when an SSL certificate expires?
Browsers show a security warning, API clients may reject the connection, and customers can experience the failure as downtime even when the application itself is still running.
How often should production SSL certificates be checked?
Manual checks are useful during launches and migrations, but production certificates should be monitored continuously with alerts well before expiration.
Keep watching after the spot check.
MarionetteOps monitors uptime paths, certificates, domains, and status pages so an expiring or mismatched certificate does not quietly become customer-visible downtime.