Focalboard is installed with Mattermost v6 and later, where it’s called Boards. You can install Mattermost as a self-hosted server or sign up for Mattermost Cloud.
The shared boards feature is disabled by default in Mattermost. To enable it:
Mattermost Boards currently uses channel-based permissions, meaning that only members of the associated channel can access (read/write) the boards for that channel.
You can use this to create private boards:
Create or join a Private channel, Group Message, or Direct Message. Then, select the Boards icon in the channel header to create a board. Only members of the Private channel, Group Message, or Direct Message can access the board.
You can use the share board feature to share a read-only board with anyone (incuding unauthenticated users) who has the generated link.
For more information about using Mattermost Boards, refer to the main product documentation here.
