TestFlight - iOS beta testing on the fly.
Responsive Viewer - View multiple screen dimensions in one view
Boombox.io - iOS devs rejoice! Embeddable HTML and hosted TestFlight beta sign-up forms.
Responsinator - Designed to test responsive websites on different devices.
Visual Studio App Center - Continuous everything – build, test, deploy, engage, repeat
Responsive Website Test - Test any website on desktop, mobile, and tablet