GFork

Shows the amount of people in the chat
- in the main/directory page
- under the player next to the viewer count



Some reasons why numbers may differ
- more viewers than chatters: bots, stream autoplays on the main page of twitch, people watch not logged in, collapsed chat or the player is fullscreen
- more chatters than viewers: bots, Chatterino users (or other chat clients)

Installation
- Install Tampermonkey or Violentmonkey extension for your browser
- Click 'Install this script' button on this page
- Click 'Install' button in the Tampermonkey/Violentmonkey extension
- Refresh Twitch page

Also available on GitHub