TestFlight - iOS beta testing on the fly.
Crystal: Sketch Mirror for Android - Crystal: Sketch Mirror for Android is an application that is designed for viewing your sketch designs in real-time, navigate prototypes and download content related to the sketches for offline viewing.
Boombox.io - iOS devs rejoice! Embeddable HTML and hosted TestFlight beta sign-up forms.
Figma Mirror - Figma Mirror is an application that covers top trending designing or sketching ideas making your teamwork in a single environment and design better products from start to finish.
Visual Studio App Center - Continuous everything – build, test, deploy, engage, repeat
Flowkit - Sketch library for user flows/content maps/annotations