Currently, there are four active developers including me. I can't speak for the others but the time to spend on the project is very rare. I can only work on it in my spare time which is between two and four hours a week. This time is mostly used for answering mails and apply patches to the repository that others sent to me.

Regards, Thomas

Erik Smeets wrote:

Just out of curiosity: how many developers are currently working on RoundCube? Follow up questions: who are they and how much time can/do they spend on development? I didn't see this mentioned anywhere in the wiki.