TestFlight - iOS beta testing on the fly.
TestFairy - Painless Beta Testing
Boombox.io - iOS devs rejoice! Embeddable HTML and hosted TestFlight beta sign-up forms.
TestApp.io - A platform that helps both mobile app developers and owners to easily share their apps with everyone to get feedback before reaching publicly to Google and App stores.
Visual Studio App Center - Continuous everything – build, test, deploy, engage, repeat
Beta Family - 50,000 testers to test your app