Click the flag top right in the header (or go to My profile → Language). Choose from Dutch, English, German or French.
The language choice is stored in a cookie that works across all Senly subdomains: `senly.io` (marketing), `app.senly.io` (portal) and your own custom domain. You don't need to choose again on every page.
The footer, UI labels and all dynamic texts follow your language choice immediately.