App Development

Kotlin 

In July 2011, JetBrains unveiled Project Kotlin, a new language for the JVM, which had been under development for a year. Kotlin is a cross-platform, statically typed, general-purpose programming language with type inference.
Google announced that the Kotlin programming language is now its preferred language for Android app developers. The Android Kotlin compiler lets the user choose between targeting Java 6 or Java 8 compatible bytecode.

Flutter          

Flutter is an open source UI software development kit created by Google. It is used to develop apllications for Android, iOS, Windows, Mac, linux and the web. The first version of Flutter was known as codename "Sky" and ran on the Android popersting System. It was unveiled at the 2015 Dart developer summit, with the stated intent of being able to render consistently at 120 frames per second.

React-Native 

React-Native is an open-source mobile application framework created by Facebook. It is used to develop  application for Android, iOS and Web by enabling developers to use React along with native platform capabilities. The working principles of react native virtually identical to React except that React Native does not manipulate the DOM  via Virtual DOM.

Swift          

Swift is general purpose,multi-paradigm, compiled programming language developed by apple for iOS, iPadOS, macOS. Swift is designed to work with Apple's frameworks and large body of existing Objective-C code written for Apple Products.