For Android and iOS you cannot really avoid it, since there are different Languages involved.
But regarding Flutter, you would write your models in Dart (as a separate library for instance) that you would use in your WebApp (via AngularDart for instance) and in your both Mobile Apps in Flutter.
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For Android and iOS you cannot really avoid it, since there are different Languages involved.
But regarding Flutter, you would write your models in Dart (as a separate library for instance) that you would use in your WebApp (via AngularDart for instance) and in your both Mobile Apps in Flutter.