We use Javascript a lot for web applications. It can be to create backends with NodeJS or to design beautiful interfaces with VueJS/Quasar. Php frameworks (Laravel, Symfony) are also commonly used by our team.
The Qt library is our main tool to create destkop applications. Qt allows us to create apps that use QML, QWidgets or web technologies for their interfaces.
The Qt library provides a very nice base to build mobile applications on both iOS and Android but Cordova is also a possibility. Our team likes to include web based interfaces into mobile app to give them a modern touch.
The perfect tech for your project is a matter of compromise. What is the best compromise given your budget, your requirements and your target? That is the question SymAlgo will help you to answer. Generally, we tend to advocate for the "code once, use everywhere and do small steps" methodology since it is fast, efficient and allows our customers to follow the progress of their apps. Companies working in science or electronics may like a C++ backend as it is extremely fast and easy to connect with their code. Others will be more comfortable with a NodeJS or Laravel server as it is very standard and easy to maintain.
We would not be a real tech company if we did not develop some framework, isn't it? By working on different projects, we acquired enough knowledge to try something: mixing Qt and web developpement patterns to create something new. We succeeded: it gave us a flexible tool to make desktop, mobile or web apps. The resulting framework is compatible with several interface technologies (Qml, Widgets, html...) and quite easy to setup. We like to use it as we can build everything with it.