Klavissimo can be used throughout in English. The language covers the app, practice and learning-path content, the AI tutor, and opt-in or code emails.
On a first visit, the device language can preselect a choice. After that, you decide under Settings → Language. The switch takes effect immediately and applies to every profile on the device.
The music stays in its original language
Work titles and names of built-in pieces are not artificially translated. Written note names do follow the chosen language: German “Cis”, for example, appears as “C#” in English.