Use issues to track ideas, enhancements, tasks, or bugs for work on GitHub. Many projects collect user feedback via a central bug tracker. GitHub's tracker is called "Issues," and can be used with every repository.
Sifter - issue tracking for nimble teams - helps keep your issue tracking simple, so you and your team can find and resolve more issues in less time. You save time and money shipping higher quality software.
ReQtest is a cloud-based software development and maintenance management tool. It supports agile development and testing of new code, as well as maintenance tasks, such as bug reporting and requirements managements.