In my opinion, the most crucial part of the process of building any product is the human-centered design. I often combine this with my knowledge in using UI tools such as Sketch.
I learnt mobile development in order to execute different projects that I have worked on. Most of my background is in React Native building for both iOS and Android. I also have a brief Android and Swift background.
Throughout the last couple of years I have worked on web development using various frameworks such as AngularJS and ReactJS in addition to vanilla HTML, JS and CSS.