Semaphor allows you to see a list of users in a particular team or channel.
LIST TEAM MEMBERS
From the team selection screen, select the blue cog next to the name of the team you are interested in. Select the option labeled ‘View…’ in the row called Users. This will give you a list of all members of the team you are looking at.
LIST CHANNEL MEMBERS
Navigate to the channel you are interested in. Once selected, there will be a small blue icon of a simplified human head and torso with a number next to it. Select this and a list of all users currently added to the channel will appear.