Flutter is a framework which will help you make apps. It is currently owned by Google. It uses Dart language to create awesome apps and has support for Windows, Mac and Linux. Some see it as a very simple method to create mobile apps. Which could be true as well considering how they treat elements as widgets and focus on them.
If you have any plan to become an app developer, you can check the link above. And, don't forget to showcase your apps here 😉