When comparing Skeleton vs Flutter, the Slant community recommends Skeleton for most people. In the question“What is the best CSS framework?” Skeleton is ranked 7th while Flutter is ranked 16th.
Ranked in these QuestionsQuestion Ranking
Pro Responsive grid
Pro Style agnostic
Pro Vanilla CSS
No bells and whistles for Skeleton, it's just CSS.
Pro Media queries
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
The developer's goal is to allow people to make apps running at 120 FPS.
Con Not maintained anymore
No active development for two years.
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.