Does this open a live connection to the domain?

No — it searches crt.sh's public Certificate Transparency log search instead of connecting to the domain itself. Browsers have no API to read a live TLS certificate's details, so this reads the public record of every certificate issued for that domain, which is accurate for almost all real HTTPS certificates (every public certificate authority is required to log certificates there) but reflects issuance records, not a live handshake.

What does "expiring soon" mean?

The current certificate expires within 30 days — time to renew it.

Why does it show more than one certificate?

The current certificate is shown first; anything below it in "Certificate history" is a previous certificate for the same domain (from a renewal or CA switch), most recent first.

What if no certificate is found?

The domain has never had a certificate logged — check the spelling, or the domain may never have served public HTTPS.

Does this tool store the domains I check?

No — the lookup runs entirely in your browser and nothing is logged or stored.

How is this different from DNS Lookup?

DNS Lookup shows how a domain resolves (A/AAAA/MX/TXT/CNAME/NS records); this tool shows its HTTPS certificate history instead — unrelated data, both looked up client-side.

SSL Certificate Checker

Look up a domain's SSL/TLS certificate — issuer, validity dates and days until expiry — from public Certificate Transparency logs.

Domain name

Looked up via public Certificate Transparency logs (crt.sh) — this reflects issued certificates, not a live connection to the domain, and no data about this domain is stored by this site.

Related tools

How it works

1
Enter a domain name

e.g. example.com — no https:// needed.
2
Searched in Certificate Transparency logs

Every public CA must log certificates it issues — that log is the source.
3
See the current certificate and its history

Issuer, valid-from/valid-until dates, days until expiry, and every hostname the certificate covers.

FAQ

Does this open a live connection to the domain?: No — it searches crt.sh's public Certificate Transparency log search instead of connecting to the domain itself. Browsers have no API to read a live TLS certificate's details, so this reads the public record of every certificate issued for that domain, which is accurate for almost all real HTTPS certificates (every public certificate authority is required to log certificates there) but reflects issuance records, not a live handshake.
What does "expiring soon" mean?: The current certificate expires within 30 days — time to renew it.
Why does it show more than one certificate?: The current certificate is shown first; anything below it in "Certificate history" is a previous certificate for the same domain (from a renewal or CA switch), most recent first.
What if no certificate is found?: The domain has never had a certificate logged — check the spelling, or the domain may never have served public HTTPS.
Does this tool store the domains I check?: No — the lookup runs entirely in your browser and nothing is logged or stored.
How is this different from DNS Lookup?: DNS Lookup shows how a domain resolves (A/AAAA/MX/TXT/CNAME/NS records); this tool shows its HTTPS certificate history instead — unrelated data, both looked up client-side.