In the same way that it’s best to work with a professional graphical designer on the icons and images in your app, it’s best to work with a professional writer on your app’s user-visible text. A skilled writer can help you develop a style of expression that reflects your app’s design, and can apply that style consistently throughout your app.
— Apple macOS Human Interface Guidelines
User interface copy
Text appears in the user interface (or “UI”) in button names, menu labels, application settings, and dialogs as well as the “microcopy” in notification banners, headings and small print, navigation, feedback and error messages.
For Wire, I maintain these user interface strings directly in open-source repositories on GitHub for each application, including:
Tone of Voice
I also maintain the Wire writing guidelines to help authors create clear and consistent content that speaks with a Wire voice and follows house style.