I was wondering if it is possible to add testers without apple account through TestFlight. I mean with just a gmail or hotmail account, because just a few of my testers have apple ID. If not is there any way to do it? Thanks!
All of your testers must have an Apple ID since without one they cannot download and install the TestFlight app from the App Store, but you don't need to know what it is.
You can add any email address as an external TestFlight tester. The email doesn't have to be an Apple ID.
The tester will receive an email with an invitation code that they redeem inside the TestFlight app. Once they redeem the code your test versions will be associated with the AppleID they are using with the App Store.