Use Qt Linguist
Most of the text to translate in an application consists of either single words or short phrases. These typically appear as window titles, menu items, tooltips, and labels to buttons, checkboxes, and radio buttons.
You mark the phrases as translatable in the QML and C++ source code. Qt localization tools provide context information for each of the phrases to help the translator understand their meaning. You can add comments to the phrases.
Translation files contain all the user-visible text and keyboard shortcuts in an application and translations of that text.
When you create a new project, you can automatically generate a translation source file (TS) for one language. To add other languages, edit the project file or go to File > New File.
To open TS files in Qt Linguist, right-click a TS file in the Projects or File System view and go to Open With > Qt Linguist in the context menu.
Use the Qt Linguist release manager tools, lupdate and lrelease, directly from Qt Design Studio. The lupdate tool synchronizes source code and translations. The lrelease tool creates run-time translation files for use by the released application.
Note: Running the tools from Qt Design Studio is supported only when using qmake as the build system. For more information about using the tools with CMake, see Qt6::LinguistTools.
By default, the project .pro file is passed to the tools as an argument. To specify other command-line arguments for the tools, go to Tools > External > Configure.
To synchronize TS files from a translator with the application code, go to Tools > External > Linguist > Update Translations (lupdate).
To generate from the TS files Qt message (QM) files that can be used by an application, go to Tools > External > Linguist > Release Translations (lrelease).
Available under certain Qt licenses.
Find out more.