In my experience, this is the best, because it is very easy to organise your working process. I like the system of filters and boards it has. I have tried other stuff too, like Asana, Jira, even Monday. Those have their pros and cons too, but to me personally Youtrack is the preferred one, due to it's simplicity and inherent minimalism. I don't do rocket science, so maybe that's why I find it the most compelling.
Jira - The #1 software development tool used by agile teams. Jira Software is built for every member of your software team to plan, track, and release great software.
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Trello - Infinitely flexible. Incredibly easy to use. Great mobile apps. It's free. Trello keeps track of everything, from the big picture to the minute details.
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WebTitan - WebTitan is an advanced DNS based web content filter and web security layer that blocks malware, ransomware and phishing attempts as well as providing web content control. Cloud and gateway versions available.