With the generalization of mobile devices and Web applications, GUI frameworks evolve at a fast pace: JavaFX replaced Swing, Angular 8 replaced Angular 1.4 which had replaced GWT (Google Web Toolkit). This situation forces organizations to migrate their applications to modern frameworks regularly so they do not become obsolete. There has been research in the past on automatic GUI migration. However, and concurrently, large organisations' applications use many dierent technologies. For example, the IT company with which we are working, Berger-Levrault, wishes to migrate applications written in generic programming language (Java/GWT), proprietary 4th generation languages (VisualBasic 6, PowerBuilder), or markup languages (Silverlight). Furthermore, one must expect that in a few years time, new frameworks will appear and new migrations will be required. Thus, there is a need for a language-agnostic migration approach allowing one to migrate various legacy GUI to the latest technologies. None of the existing solutions allow to deal with such a variety of GUI framework. They also typically focus on a subpart of the migration (\ie how to extract a specific GUI framework) ignoring the re-engineering/forward-engineering part of the migration (which is straightforward for a single technology). This makes it difficult to adapt these solutions to other GUI frameworks. We propose an approach to migrate the GUI part of applications. It is based on meta-models to represent the visual element structure and layout. We detail how to create both the GUI extractors and generators, with guidelines to support new markup and programming languages. We evaluate our approach by implementing three extractors and generators for web-based or desktop-based user interfaces defined with generic programming languages (Java, Pharo, TypeScript) or markup languages (XML, HTML). We comment case studies on five applications, opened and closed source, of different sizes. The implementations of our generic approach detect 99\% of the widgets and identify (\ie determine the type of the widget) \pourcentageWidgetBienIdentifier of them. We give examples of the migrated GUIs, both successful and not.