Here is a useful alternative. Compatible on Windows, Mac and Linux
Stop paying hefty bills and start using Aitum Multistream! Aitum Multistream allows you to stream everywhere from a single instance of OBS.Twitch, YouTube, TikTok, anywhere and everywhere you want. If you use Aitum Vertical, great news! Aitum...
obsproject.com
It's a nice alternative, but it lacks a couple of features the Multiple RTMP Output plugin has, most notably, the ability to tell individual encoders to turn on and/or off when you use the start/stop streaming button on OBS Studio. Aitum requires you to switch individual encoders manually on and off, and no way to "gang" them together with OBS Studio's "start/stop streaming" button.
Others have mentioned other features that Aitum should have as well.
The other feature Aitum has, vertical streaming, I can't find a use case for it. I would also have to reengineer my infrastructure to handle this kind of workflow, either separately or in parallel with the normal horizontal canvas.
All that said, despite the vertical streaming options, the moment the ganging feature I cited gets added, I will be all over this.
--Katt. =^.^=