In one embodiment, a client device may send one or more sub-session requests to one or more corresponding session controllers through a computer network to obtain one or more corresponding sub-session tokens that indicate in which sub-sessions of an online collaborative computing session the client device is permitted to participate. The client device may then receive particular sub-session tokens (e.g., based on certain permissions), which may then be sent to a collaboration server to establish one or more permitted sub-sessions of the online collaborative computing session with the client device as indicated by the received sub-session tokens.