It is a C++ library that lets developers create applications for Windows, macOS, Linux and other platforms with a single code base. It has popular language bindings for Python, Perl, Ruby and many other languages, and unlike other cross-platform toolkits, it gives applications a truly native look and feel because it uses the platform's native API rather than emulating the GUI. It's also extensive, free, open-source and mature.
It is a feature-full, plugin extensible IDE for C/C++ and many other programming languages. It offers a seamless development environment to programmers that work on projects of any size. It helps you get the job done while staying out of your way.
Flutter is a mobile app SDK to help developers and designers build modern mobile apps for iOS and Android.