A monitoring tool for certificate transparency of ProtonMail's SSL/TLS certificates
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ct-monitor.py Improved date handling, Changed API endpoint. Feb 15, 2018
license.md Added license. Jul 11, 2017
requirements.txt Initial release. Jul 11, 2017



A monitoring tool for certificate transparency.


The tool monitors and logs new changes on certificate transparency for domains. It then notifies the user whenever a new certificate has been logged on the certificate transparency framework. In case an unauthorized signed SSL certificate for a domain is created, it will be immediately logged and notified.


Let's say a company owns example1.com, example2.com, example3.com, etc... To monitor the certificate transparency logs for these domains.


python ct-monitor.py --domains "example1.com,example2.com,example3.com" --db /var/logs/ct_monitor.db --initial-scan


After running an initial scan on all domains, run the following:

python ct-monitor.py --domains "example1.com,example2.com,example3.com" --db /var/logs/ct_monitor.db

Now, whenever a certificate is issued that holds one of the specified domains, a notification will be sent.


Within the ct-monitor.py script, there is a function called notification_handler. It's set to print the notification on screen by default. You would need to customize it based on your needs to integrate the tool with your preferred notification channel.


  • Python2 or Python3
  • requests


The project currently supports all platforms that run Python. The project is compatible with both Python 2 and Python 3.

References on Certificate Transparency