It depends on all the functionality you need. Not everything in JIRA is exposed via REST APIs and hence you might need a plugin in some cases.
I would recommend taking a look at existing products like ConnectAll (developed by my company) and see if that works for you. I know that it works between Cloud and on-Premise instances.
Hi all! My name is Miles and I work on the Marketplace team. We’re looking for better ways to recommend and suggest apps that are truly crowd favorites, so of course we wanted to poll the Community. ...
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