TestFlight - iOS beta testing on the fly.
Boombox.io - iOS devs rejoice! Embeddable HTML and hosted TestFlight beta sign-up forms.
TestFairy - Painless Beta Testing
DeployGate - DeployGate enables developers to distribute beta apps to enable beta testing from fellow developers and community.
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.
BoardingBot - Send TestFlight invites automatically