Redmine is an adaptable open source project management application and it carries everything you need to manage your workflow such as scheduling, roadmaps, calendars, Gantt charts, version management, document management, news, files, activity views and more. You are also able to plug in other applications that you are using to Redmine as well.
However, Redmine is not only a project management tool, it can also be used as an issue tracker due to its fully configurable workflow, where you can change issue statuses and field values for every role-tracker pair individually. It also carries issue tracking features like priorities, subtasks, subscribing, commenting, custom field, filters and so on.
Beyond that, Redmine also allows you to share ideas with your team and manage their knowledge. Users can manage multiple projects in one place and administrators can assign team members to different projects and roles
Being an open source application, it means that anyone can download the code and add to it, hence the community has added a lot of useful features to the app over the years and they are always looking to improve it and add new features to it.