Anonymous comments and comment rooms can improve privacy and facilitate user activity in a collaboration content item system. Some embodiments include a method for anonymous comments that can include receiving a request to add an anonymous comment to a collaboration content item. The method can further include generating an anonymous user identifier for a user associated with the request. The method can further include inserting the anonymous comment in the collaboration content item with a representation of the anonymous user. The representation can include an anonymous avatar generated based on the anonymous user identifier. Some embodiments may include comment rooms for collaboration content items. Multiple users are associated with a comment room. 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.