Check out ZenHub -
It adds these features to improve the GitHub Issue tracker directly into GitHub.com, allowing you to:
- Display issues on a task board by priority and progress - Attach any file type to an issue - Add estimates and view burndown charts / metrics attached to them - +1 issues to avoid excess comments - Improved search functionality - Link repos together to view issues that span multiple projects
Without having to context switch out to a separate issue tracker or UI
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Disclosure - I work at ZenHub, and use it with GitHub all day :D