SSL / TLS Certificate Checker
Inspect the SSL / TLS certificate for a domain, including issuer, validity period, subject alternative names, OCSP URLs, TLS version, and certificate chain.
Enter a domain name to inspect its SSL / TLS certificate.
Certificate summary
IdleOCSP URLs
Subject Alternative Names
Certificate chain
Raw JSON
What is an SSL / TLS certificate checker?
An SSL / TLS certificate checker helps you inspect the HTTPS certificate served by a domain.
It is useful for checking expiration dates, issuer details, subject alternative names, supported TLS information, OCSP endpoints, and the certificate chain.
How to use the SSL / TLS Certificate Checker
- Enter a domain name.
- Optionally adjust the port if needed.
- Click Check certificate.
- Review validity, expiration, issuer, SANs, OCSP URLs, and raw JSON details.
Tips
- A certificate may be valid but still expire soon.
- Subject Alternative Names show which hostnames are covered.
- The issuer helps identify which CA issued the certificate.
- Raw JSON is useful for debugging or automation.
SSL deployment checks
Hostname coverage
Confirm the certificate covers the exact hostnames users visit, including www, apex domains, API subdomains, and regional hosts.
Expiration monitoring
A valid certificate can still expire soon. Monitor the valid-to date and renew before deployment freezes or holidays.
Certificate chain
Missing intermediate certificates can break older clients even when the leaf certificate looks valid.
DNS and CDN changes
After moving DNS, CDN, or load balancer settings, recheck the certificate served by the final public endpoint.
Related guides
Learn the workflow behind this tool and what to check next.
How to validate a domain before launch
A launch workflow for confirming DNS records, domain ownership signals, SSL coverage, and security headers on the public endpoint.
How to troubleshoot DNS records for a domain
A practical DNS checklist for website hosting, email records, domain verification, nameserver changes, SSL certificates, and reverse DNS.
Technical SEO checks before submitting a site
A focused checklist for making sure search engines can discover, crawl, understand, and index important pages.
SSL certificate checks before deployment
Certificate problems often appear only after DNS, CDN, or load balancer changes. Check the public endpoint before and after deployment.
Hostname coverage
Confirm the certificate SAN list covers the exact domain, subdomain, wildcard, or alternate host users will visit.
Expiry window
Review days remaining and renewal behavior before a certificate approaches expiration or an automated renewal fails.
Chain completeness
Check issuer and chain details so browsers, bots, and older clients can build a trusted path.
Correct endpoint
Test the real public hostname and port after CDN, proxy, or load balancer changes, not only the origin server.
Privacy and usage
Built for quick checks without an account
Toolinix tools are designed for short developer tasks: paste a safe sample, inspect the result, copy what you need, and move on.
No login required
You can use the tools without creating an account, subscribing to a newsletter, or saving a workspace.
Local when possible
Formatters, generators, encoders, and text utilities generally run in your browser. Network diagnostics may need a server-assisted lookup to check public URLs, domains, or IPs.
Keep secrets out
Do not paste production passwords, private keys, access tokens, customer records, or regulated data into online tools unless your own security policy allows it.
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