You can use ActiveCollab in Czech, Dutch, French, German, Italian, Polish, Portuguese, Swedish, Spanish, Turkish, Hungarian, Croatian, Serbian and Russian.
Changing language is easy. Once you're in ActiveCollab, click on your avatar in the top-right corner and then click Profile. There you set your personal preference for the language.
Want to change the language for all new users? When you invite someone, they can start using ActiveCollab right away in your native language. You can do that in System Settings** > **General Settings.