Sketch is a fantastic tool for designing user interfaces. One of the best new features Sketch got in 2016, was the ability to specify how an object will be resized when the parent element changes its size. This contextual setting was a boon for designers working on responsive websites and mobile application designs. For me, it cut down the need for multiple symbols, as now, one symbol can be easily reused in many instances. As with any new feature, this was not perfect. In multiple instances, it was impossible to use a symbol if the symbol needed to change its size on both, horizontal and vertical axes.
I've been eyeing Figma for a while, and I was impressed by their complex and awesome constraint system. However, as much as I like some aspects of Figma, I find it unusable for real work.
Enter Auto-Layout from the guys at Anima App.
Auto Layout not only lets you define the sane constraints for your elements, but it also lets you easily test and explore how your design looks on various device sizes. While this feature is obviously useful for mobile app designers, the constraints settings are extremely useful for designing responsive websites as well.
You can download Auto Layout from their Github page.