How to distribute ios applications bypassing the AppStore?

Question

Apple Developer Program

We have an ios application that we don't want to release in the AppStore for our own reasons.
But you need to distribute it somehow, as a demo for customers.
iTunesConnect allows you to distribute an application by specifying the user's email from the AppStore?
What I found myself:
I heard about iOS UniversalDistribution, when you can download the app from the link and install it like in android with an alert that the software is self-signed. But this requires an enterprise license, which is expensive and difficult to obtain.
Apple TestFlight
HockeyApp
Ubertesters
Crashlytics
don't fit either. since above users to register in advance in the system, and we need to give access to the application on request, for example, during a demonstration.
Colleagues, tell me how to install an application on an Ios device (NOT jailbreak) without the AppStore

Answer 1

What's wrong with Apple TestFlight? For access, you only need the user's apple id and that's it.
There are no other options.

Answer 2

sign up for the iOS Developer Enterprise Program for $299/year, you will be able to create In-House Apps. Read in detail https://developer.apple.com/programs/ios/enterprise/
Another link to a small instruction on Habré habrahabr.ru/post/160087