I want to show a notification when a task assign a high priority by admin.I don't know which task is medium,low and high priority so, i want an alert notification on high priority task.
in case e-mail is okay as for the medium of the notification you could have a look at "filter subscriptions".
You can use them in Jira with no additional cost (compared to a special App).
The basic idea is easy, you define a JQL query, save it as a filter and a defined group receives a nice overview of all issues that match. This might be not sufficient when the "alert" has to be "immediately" sent out. But if a hourly (or so) overview is okay then it is a very nice and easy implementation.
Further information is to be found in a blog post from some years ago...
... as well as in official documentation
There are many approaches how you alternatively can achieve your goal. I am sure other users will contribute with some additional ideas (for example Automation is a modern way you also could use nowadays).
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