This article will compare Flutter and Ionic. both this two technologies will helps build mobile apps, but there are some differences between those two framework. which one is the best choice for your next mobile project? let's dig a bit in this subject.

Flutter

flutter logo Flutter is an SDK (software development kit) and a Dart framework, Dart a programming language developed by Google. Flutter itself is also developed by a Google team.
Flutter is an open source Google's mobile UI framework which has shown the right way for developers to build mobile applications for iOS and Android. The building of apps and interfaces has been made possible by using a single codebase that is compiled directly to native arm code which makes it easier to access platforms APIs and services. Flutter allows the developer to make their mobile app in no time and also it uses Stateful Hot Reload feature that allows developers to change the code of the application without losing its state. The idea behind Flutter is that you write Dart code which can be compiled to native code that runs on the target device. You use Dart the Flutter framework to build user interfaces composed of so-called widgets. Flutter ships with a bunch of pre-configured widgets (buttons, tabs, side navigation etc) and you typically use these to then also build your own, more complex widgets.

There plenty of apps developed with Flutter framework and big companies are switching to use flutter for building business applications.

Flutter also gives you the possibility to have complete control on every pixel on the screen by moving the widgets or adding gestures, animations or rendering into the framework which gives you the flexibility to build custom designs. Flutter framework also allows you to add platform conventions and interface details such as navigation, icons, fonts, scrolling and more. This framework is also great for both new and experienced developers.

For all those reasons, Flutter is the best framework right now to build native mobile apps.

Ionic

ionic logo Ionic is a javascript to build hybrid apps, it's one of the easiest frameworks to learn and start from the first days to build productive apps, however it's a hybrid framework, that means those apps are not completely native applications even if they looks like normal native apps.
With ionic framewrk you create a web app (with HTML, JS and CSS) which will be wrapped by a real native app that hosts a webview (basically a hidden browser). Since you build a web page in the end, Ionic is pretty easy to get started with for web developers.
Now with Ionic 4, Ionic is basically a huge suite of components you can use (buttons, cards etc) with any frontend framework (or none at all).

Ionic is pretty popular. It's basically directed to (web) developers to build native mobile apps in the fastest possible way. with 35k stars on githubr, we can see that it gains a lot of popularity right now.
Ionic uses Cordova or its own solution, Capacitor, to give you access to native device features. It provides a very decent set of packages to access common native device functionalities like the camera. You can also write your own wrappers around native functionalities and then include them in your code of course.

Learn Ionic Framework

What should I choose Ionic or Flutter?

First of all, you have to decide whether you want to stick to the native language and Dart program*ing language and accept the disadvantage of learning two things and writing code with this new language. This is a lot of work and mastering Dart and Flutter framework. Then you should absolutely choose Flutter without doubt, because you definitely will benefit from it's advantages and have some great fast and efficient mobile apps for both platforms (ios and android).

If you don’t want to use the native language or learn a new language at all, and maybe you already are a web developer with years of experience in HTML, CSS, Javascript then choose ionic because it's gonna be easy for you to learn and start building mobile apps. (more details about ionic framework)
But if performance is super-important to you - or you need to access a lot of (advanced) native device features - you might want to take a look at Flutter.