Wherever possible we'll use the user-agent of:
Janitor - https://getjanitor.com/
By using a unique user-agent like this you should be easily able to find us in your access logs and most analytics packages.
We use a number of different methods to visit your websites, depending on the check being run. For example, checking your website uptime is done in a differently to the way we approach crawling your website for mixed content. However, we always aim to use the same user-agent so you can easily identify Janitor.