OBS Remote Control

Head to the obs-websocket releases page: https://github.com/Palakis/obs-websocket/releases (linked from the resources section of the OBS site itself)

Download the installer.exe and run it. That will install the plugin.

Start OBS. In the Tools menu there should now be an option Websocket Server Settings:

 

 Make sure "Enable Websocket Server" is checked. You can turn on authentication if you want.

We will need to know the IP address of the machine running OBS. There's a bunch of ways to find this. The one I usually use is windows key+R and type cmd:

Run ipconfig, you're looking for the IPv4 address:

 

On your tablet or phone (which must be on the same network), open a browser and head to http://t2t2.github.io/obs-tablet-remote/ and bookmark it so you don't have to remember that later.

Enter the IP address we found above and press connect. You should then have a simple interface that will allow you to transition scenes:

You can add additional tools like start/stop recording/streaming, change transitions, etc. By pressing the pencil. For example, because I'm using a phone, I changed the horizontal split to vertical, the scene switcher from 4 to 3 columns and added the start/stop streaming buttons underneath:

By nesting splits, you can get quite a complex but useful layout. e.g.

becomes

It'll remember your layout between sessions. If you get in a mess, the cog can reset the layout to the default.