TestFlight - iOS beta testing on the fly.
DeployGate - DeployGate enables developers to distribute beta apps to enable beta testing from fellow developers and community.
Boombox.io - iOS devs rejoice! Embeddable HTML and hosted TestFlight beta sign-up forms.
Applivery - Mobile Apps distribution system for Continuous deployment, Beta testing, Feedback, Bug reporting & Enterprise App distribution.
Visual Studio App Center - Continuous everything – build, test, deploy, engage, repeat
Beta Family - 50,000 testers to test your app