Logo
SSL / TLS lookup·issuer · expiry · grade

Is that certificate trustworthy?

Check any domain's SSL/TLS certificate — issuer, validity window, protocol, cipher strength, and a security grade — in one request.

Live TLS handshake
A+ to F grading
Enter a domain to check its SSL certificate.
Try google.com, github.com, or your own domain.
What you get

SSL, graded instantly.

We perform a live TLS handshake against the domain's certificate and translate the raw output into a clear pass/fail with a letter grade.

Live TLS handshake

We connect to port 443 and inspect the certificate the server actually presents — not cached or third-party data.

A+ to F security grade

Protocol version, cipher strength and certificate validity are combined into a single grade, so you know at a glance if it's solid.

Expiry warnings

Certificates expiring within 30 days are flagged so you can renew before visitors see a browser warning.

Full chain detail

See the issuer, subject, alternative names (SAN), fingerprint and whether the certificate chain is complete.

Stop second-guessing.

Find your domain in the next 30 seconds.

Free forever. No login required. 1,100+ TLDs in one query — plus AI suggestions and the premium marketplace.

Start checking now Learn more
1,147
TLDs
200ms
Avg lookup
100
Suggestions/query
FAQ

SSL, explained.

It encrypts traffic between a browser and the server, and proves the server is who it claims to be. Without a valid certificate, browsers show a warning and refuse to send data securely.
The grade weighs the negotiated TLS protocol version, cipher strength, and whether the certificate is currently valid and complete. Weak protocols (like TLS 1.0) or ciphers pull the grade down even if the certificate itself hasn't expired.
Browsers block the page with a full-screen warning and most visitors leave immediately. Set a calendar reminder well before the expiry date shown here, or use a host with automatic renewal (e.g. Let's Encrypt).
HTTP Strict Transport Security tells browsers to only ever connect over HTTPS for a domain, even if a user types http://. It closes a window attackers can use to downgrade a connection to plain HTTP.
Browsers trust a certificate by following it up to a trusted root through intermediate certificates. If a server doesn't send those intermediates, most browsers still work (they cache them), but some clients and API tools will fail to verify the connection.