SSL Certificate Checker
Confirm that an SSL certificate is correctly installed on a server
Features
Instantly check the validity period
Show the remaining days and expiry status with color-coded badges
Inspect the certificate in detail
Covers the issuer, serial number, and fingerprint
List covered domains
Check multiple domains via the SAN (subject alternative name)
Retrieve TLS connection info too
Also show the port number and protocol version
How to use
Enter the hostname
Enter the domain name or hostname you want to check in the input field
Check with the run button
Press the run button to make a TLS connection on the server side and retrieve the certificate
Review the certificate info
Review the validity period, issuer, SAN, and detailed info in a list
Use cases
Prevent certificate expiration
Regularly check the remaining days to avoid errors from missed renewals
Verify HTTPS settings
Verify that the certificate was installed correctly after building the server
Confirm covered domains
Check via the SAN whether the certificate covers the intended domains
Investigate the certificate's issuer
Determine whether it is a legitimate certificate from the issuer and serial number
Basic Knowledge
What happens when a certificate expires
When a site's certificate expires, the browser displays a full-screen warning, causing most visitors to leave. Since this occurs even when the site displays normally, regular deadline checks are fundamental to operations.
What is an intermediate certificate
An intermediate certificate is a bridge certificate that connects a server certificate to the root certificate authority. If forgotten during server installation, it can cause trust errors in only some environments, making it a difficult-to-diagnose issue.
Safety and privacy
Server-side processing
Input is processed on the server; only information necessary for the inquiry is sent.
Temporary processing only
For checking the SSL certificate, temporary processing occurs on the server, then data is discarded after results are returned.
Communications encrypted with HTTPS
All sent and received data is encrypted by TLS and cannot be read by third parties.
No transmission to third parties
Input content is not sent to external services such as ad networks or trackers.
Connects only to the target host
It makes a TLS connection to the entered host to retrieve the certificate, and the content is not shared externally
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RAKKOTOOLS is free to use!
Available free of charge for individuals and corporations, commercial and non-commercial use alike.No prior permission or usage application is required. Feel free to use it in various situations.
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Use in schools, work, and events
Can be used in various situations such as classes, team division, internal work, and events.
Introduction on Web, books, and SNS
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Commercial use
Can be used for commercial purposes such as research, calculation, processing, and conversion in business and production.
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If using in streaming and videos
Link to RAKKOTOOLS in the description, or Mention or display that you are using RAKKOTOOLS in the stream or video.
Credit example for the description
Usage guidelinesYou are free to use it for normal purposes. However, use for purposes that violate laws, infringe on third-party rights, impose significant load on the service, or otherwise interfere with service operation is prohibited.
We do not guarantee the accuracy or completeness of information and calculation results obtained from each tool.
This notice is a translation of the original Japanese text. If there is any discrepancy between the translation and the original, the Japanese original takes precedence.