When comparing Flutter vs Cirrus, the Slant community recommends Cirrus for most people. In the question“What is the best CSS framework?” Cirrus is ranked 23rd while Flutter is ranked 25th. The most important reason people chose Cirrus is:
Supports both Flexbox and CSS grid making it a great modern choice for designing web apps.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Open source
Pro Great developer tools debug/hotreload/analyser
Pro Based on Dart language
Dart is a Java like language, easy to learn and startup fast for millions of Java developers.
Pro A single codebase for iOS AND Android
Pro Fast
The developer's goal is to allow people to make apps running at 120 FPS.
Pro Supports Flexbox and CSS Grid
Supports both Flexbox and CSS grid making it a great modern choice for designing web apps.
Pro CSS Only
No additional JS/jQuery required to use.
Pro Mobile Responsive
Extremely responsive and supports many smaller screens.
Pro Open Source
Open source and quite actively maintained on Github.
Pro Lightweight
Much smaller than Bootstrap with just as much flexibility.
Cons
Con Still in development
According to the website, Flutter is still in its early stages of development.
Con Based on Dart language
Dart is a Java like language, easy to learn and startup fast for millions of Java developers. BUT if you have to learn it ... it's a con.
Con Dart is unpopular and never gained serious community traction like Kotlin or Java
Con Does not support 32-bit iOS devices
If you plan on targeting iPhone 5, 5C or earlier, you can forget about Flutter.