SSL Certificate Checker
Look up SSL/TLS certificate details for any domain — issuer, expiry date, SANs and validity. Data comes from Certificate Transparency logs, with a live HTTPS reachability check from your browser.
🔒 No certificate is fetched directly. The lookup queries public Certificate Transparency logs.
💡 Finding This SSL Checker Useful?
Get the standalone version — a single HTML file you can keep on your machine and open anytime, with no scripts loaded from anywhere.
🛒 Get the Standalone Version🔍 What Is an SSL Certificate Checker?
An SSL Certificate Checker retrieves information about the TLS certificates issued for a domain. It answers three practical questions: when does the certificate expire, who issued it, and which domains it covers. This tool pulls that data from Certificate Transparency (CT) logs — public, append-only records that every browser-trusted Certificate Authority must submit to. It then runs a live HTTPS reachability check from your browser to confirm the site is currently serving a valid certificate.
✨ Key Features
Expiry Countdown
See the exact expiry date of the most recent certificate and how many days remain before it lapses.
Issuer Identification
The certificate's issuing authority is extracted and shown by organisation and common name.
SAN Coverage
See every hostname the certificate covers — useful for confirming whether www and the apex domain are both included.
Live HTTPS Check
Your browser attempts a real HTTPS connection to the domain. If the TLS handshake succeeds, the currently served certificate passes validation.
Certificate History
See the most recent certificates issued for the domain, with validity periods and issuer details for each.
No Direct Certificate Fetch
The tool does not connect to your target server to read its certificate. It uses public CT log data plus a standard browser HTTPS request.
📖 How to Use the SSL Certificate Checker
- Enter a domain — type it with or without
https://. Paths and ports are stripped automatically. - Click Check certificate — the tool queries Certificate Transparency logs for issued certificates and runs a live HTTPS check.
- Read the status card — it shows whether the most recent certificate is valid, expiring soon, or expired.
- Review the details — issuer, validity dates, days remaining, and SAN coverage.
- Check the live badge — confirms whether your browser can establish a valid HTTPS connection right now.
- Browse the history — the most recent certificates issued for the domain are listed below.
🎯 Practical Use Cases
Expiry Monitoring
Confirm a certificate is not about to lapse, without logging into a hosting panel.
Checking www vs. Apex
See whether example.com and www.example.com are both covered by the same certificate.
Issuer Verification
Confirm which Certificate Authority issued a domain's certificate — useful during migrations.
Subdomain Discovery
SAN entries often reveal subdomains the domain owner may have forgotten about.
Post-Renewal Confirmation
After renewing a certificate, verify that the new one appears in CT logs and covers the expected names.
Client Reports
Gather a quick certificate summary for a site audit or handover document.
⚠️ Important Notes and Limitations
This tool uses Certificate Transparency logs, which are public but not a live TLS handshake. A few honest caveats:
• CT logs are historical records, not live checks. The certificate shown is the most recent one logged for the domain. The server might be serving a different certificate (older or newer) at this moment. Use the live HTTPS badge as a complementary signal.
• The browser cannot read the served certificate's details. JavaScript has no API to inspect the expiry date, issuer, or SANs of the certificate currently served by a domain. That is why this tool relies on CT logs, which are a reliable public proxy.
• CT log data can lag. A certificate issued minutes ago may not appear immediately. Newly deployed certificates typically appear within a few minutes to a few hours.
• Not every certificate is logged. Publicly trusted CAs must log certificates, but private/internal CAs and self-signed certificates typically do not appear in CT logs. If a domain uses an internal CA, this tool will find nothing.
• crt.sh can be slow or rate-limited. The tool sets a 20-second timeout. If the lookup fails, wait a moment and try again.
• The live check only confirms TLS handshake success. It does not read the certificate. A successful handshake means the browser accepted the certificate, but the tool cannot tell you which certificate was served.
❓ Frequently Asked Questions
Partly. The certificate details (issuer, expiry, SANs) come from Certificate Transparency logs — public records of every certificate ever issued for the domain. These logs are maintained by browser-trusted CAs and are the same data sources used by tools like crt.sh. The live HTTPS badge performs a real TLS handshake from your browser, which confirms the site currently serves a certificate the browser accepts. What the tool cannot do is read the served certificate's expiry date directly, because browsers do not expose that to JavaScript.
Your browser shows the certificate currently being served. This tool shows the most recent certificate logged in Certificate Transparency. If the server is serving an older certificate that was renewed but not yet deployed, or if a newer certificate was logged but not yet deployed, the dates may differ. The live badge tells you whether the currently served certificate is accepted by your browser.
Certificate Transparency (CT) is a public logging system that requires Certificate Authorities to submit every certificate they issue to append-only logs. This allows anyone to monitor certificate issuance, detect mis-issuance, and discover subdomains. Every major browser trusts certificates only if they appear in CT logs, which is why the data is comprehensive for public certificates.
It works for any domain with publicly trusted certificates logged in CT. It will not find results for domains using only internal or self-signed certificates, and it cannot inspect certificates on non-standard ports or behind private networks.
You are querying public data. The domain you enter is sent to crt.sh as part of the CT log search. No certificate is fetched from the target server, and no credentials or personal data are involved. The live HTTPS check is a standard browser request to the domain you specified.
Not automatically from this page. The tool is a manual lookup. For automated monitoring, you would need a script or service that queries CT logs or performs TLS handshakes on a schedule. The standalone edition of this tool can be run locally and adapted for that purpose.
👨💻 About the Author — GenieDevs
📦 Get the Standalone Version
🔐 SSL Certificate Checker – Standalone Edition
One self-contained HTML file with the full checker inside. Keep it on your machine or run it locally in an offline environment — no external scripts required for the core lookup.
✅ Final Takeaway
Certificate expiry is one of those problems that is trivial to prevent and expensive to discover at the wrong moment. This tool gives you a fast, browser-based way to check when a domain's certificate expires, who issued it, and which names it covers — without logging into a hosting panel or running openssl. The CT log data is public and comprehensive for publicly trusted certificates, and the live HTTPS badge confirms the site is reachable right now. Use it during deployments, migrations, or whenever you need a quick certificate sanity check.