What is the app?
ScriptRunner from Adaptavist
How did you find the app?
We found the app on Atlassian Marketplace early in our Jira journey
What did you use it for?
Wow, it is probably easier to answer "what is it NOT used for?" 
We use it to run post-function scripts in many of our workflows, use the added functions in JQL's, watch for certain types of issues and update them, etc. We also use it to run scripts on demand whenever we want to change some values on issues or projects, some examples are:
- to change a value in a custom field
- change Security Level on certain issues
- delete all but two projects (like when we create an "empty" test instance
- find where a certain AD group is used in a certain Project role
- remove values from a role
- send email to Assignee's when issues go past due date
- transition issues from "Pending Closure" to "Closed" after 5 days of inactivity
Which team used it?
Really everyone because of the added functions in the JQL, like searching for all sub-tasks that have a parent with certain attributes. However, the admins mostly use it to fulfill business requirements that come from cross functional teams.
What would happen if you didn’t have it?
We'd be a bunch of sour patches if we didn't have ScriptRunner, it really does so much for our Jira instance. It really works wonders!
