1. JIRA

Overview: Developed by Atlassian, JIRA is one of the most popular issue and project tracking tools.

Features:
Customizable workflows and dashboards.
Integration with other Atlassian products like Confluence and Bitbucket.
Robust reporting and analytics capabilities.
Support for agile methodologies with features like Scrum and Kanban boards.
Use Case: Widely used by agile teams for defect tracking and project management.

2. Bugzilla
Overview: An open-source bug tracking tool developed by the Mozilla Foundation.

Features:
Advanced search capabilities and customizable dashboards.
Detailed bug reporting and tracking.
Email notifications and permissions management.
Extensive integration options with other tools.
Use Case: Suitable for open-source projects and organizations looking for a free, customizable solution.

3. Kualitee
Overview: A cloud-based test management tool with integrated defect tracking capabilities.

Features:
Comprehensive test case management.
Customizable defect tracking and workflows.
Integration with JIRA, Selenium, Jenkins, and other tools.
Detailed reporting and analytics.
Collaboration features such as comments and attachments.
Use Case: Suitable for teams looking for an all-in-one test management and defect management tools in software testing solution with strong integration capabilities.

4. Redmine
Overview: An open-source project management and issue tracking tool.

Features:
Flexible issue tracking with customizable fields and workflows.
Support for multiple projects.
Gantt charts and calendars for project planning.
Time tracking and file management.
Use Case: Used for both project management and defect tracking, especially in environments where flexibility and customization are important.

5. MantisBT
Overview: An open-source bug tracking tool known for its simplicity and ease of use.

Features:
Simple and intuitive user interface.
Email notifications and role-based access control.
Customizable workflows and fields.
Integration with various version control systems.
Use Case: Ideal for small to medium-sized projects needing a straightforward bug tracking solution.