As a SharePoint power user you probably face with a task of advanced field managing in list item forms. You might need to hide or disable a field in a list item form before it is displayed to a user, depending on some condition you define. FormDesigner is a cutting-edge application for SharePoint 2013 which enables you to do so easily!
It’s implemented as an app part that can be added to Display, Edit or New list item form (only ListFormWebPart is supported). The app part has a few of simple properties. Conditions for visibility and availability of fields are defined in a XML settings file which is stored in the settings library of the app.
This is a full version of the app, it is licensed per farm with no user limitation and subscription.
PLEASE USE THE "for more than 1 person in your organization" OPTION WHEN BUYING THE APP.
The free demo version named FormDesigner Demo is also available on the store.
Both versions of the app can be used on Office 365.