Anonymous comments and comment rooms can improve privacy and facilitate user activity in a collaboration content item system. Some embodiments may include a method for providing comment rooms for collaboration content items. Multiple users are associated with a comment room for a collaboration content item. Comments, annotations, or content updates to a collaboration content item performed within a comment room are visible only to the users associated with the comment room. The system can manage different versions of a collaboration content item, having different comments, annotations, or content for each comment room. A comment room may include anonymous comments. An anonymous comment for a collaboration content item is presented with a representation of an anonymous user, such as an anonymous avatar generated based on an anonymous user identifier of the anonymous user.