Ranked in these QuestionsQuestion Ranking
Pro Test plan manager
Includes a manager for testing plans.
Pro Free unlimited projects & team members
Lean Testing is free for an unlimited number of team members or projects.
Pro Slack integration
Can easily be integrated with Slack.
Offers a hosted version, which is very helpful if you want to avoid the time and energy it takes to host a bug tracker on your own internal server.
Con Not very popular
Since it's not a very popular solution, there are not as many guides and resources for this out there. Plus, there's also a greater risk of it shutting down one day than other, more popular issue trackers.