DevOps Manager for Azure DevOps (formally VSTS) is the only app you need. It allows you to manage your devops projects.
This app features your project one-stop-shop. Access everything you need from one page. View active work items, view repository commits, pull requests and even start a build.
Work Item Management:
Create, view and edit your work items on the go. With support for all work items and all possible fields. Link work items together and view them. Easily change state and who a work item is assigned to all from the same screen.
Easily view the work items assigned to you across all your projects from the main screen. Collaborate with fellow developers using the comments.
Help shape the app and decide upon the features being implemented. See and vote on what others suggest.