I have used many defect tracking systems over the years but FlySpray is the best.
When I first started writing software our defects and enhancement requests were tracked on triplicate carbon forms. Yes, I'm that old! :-) The developer assigned an issue had a copy, the Project Manager had a copy and the Quality Assurance team had a copy. Every week we would get together and go over new issues and progress, each of us with our forms.
Since then I have used StarTeam, TeamTrack, Alexis Team!, SQA, BugZilla, and others I can't remember but I didn't like any of them. Sure, they were better than keeping up with triplicate forms but they were always in your way. I don't like software that invades your life and takes over. It sould just be there when you need it.
Enter FlySpray. I rather like FlySpray. It is simple, clean, easy. People enter bugs, I see them. They can have comments, attachments, history. Nothing fancy, just there with what I need. It is very easy to customize as well. I hated commenting on a bug everytime I checked in a fix. So I wrote a simple script that would insert the comments for me. Open code, open database, open source. Nothing I have said is new to defect tracking software. FlySpray just stays out of my way.
I have used FlySpray for over two years and it is stable even without the 1.0. 0.9.9 has just been released - go get it!
