You can use this free website to watch up to 6 Twitch streams at the same time, as long as your computer and bandwidth can handle it!
I’ve built it to watch tournaments without the need of arranging multiple windows and to make it easy to share. I hope you’ll enjoy it!
Simply add the streamers you want to watch by clicking the "Add a Streamer" button on the left bar.
As an alternative, you can put the twitch usernames in the url
Multistream will provide you a default layout for your streams that you can later change.
You can also rotate them to let you focus on the stream you prefer by accessing the left bar.