Sidehistorik
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One of my favorites, one of the reasons being that it is free 
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Update 2017-10-02: Well, its not free anymore |
And its actually integrated into JIRA Cloud now. But for onPremise, its for purchase....
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The Scriptrunner is free, and most of the Conditions, Validations and Post-Functions that other plugins on this page offer, can be achived for "free" in groovy. But its all "by hand" - whereas several plugins offer a GUI and other value added fields etc. |
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Update 2017-10-02: Well, its not free anymore, since the writing of this article, Adaptavist has purchased Scriprunner. But, its still the best JIRA Plugin by far |
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