Sketch is a prototyping app similar to Adobe XD, Axure RP, Framer, Figma, and Invision Studio.
Sketch costs $99 per year for a subscription. There is no free version of Sketch, but there is a student version available at 50% discount.
Sketch files can be viewed in a browser with Sketch Cloud. The Sketch editor is only available for Mac.
Unique Advantages
Sketch is one of the oldest and most established prototyping apps and built a large following on Mac. It has a huge library of plugins.