Reddit Account Switcher от Slyke

Reddit Account Switcher is a Firefox WebExtension for people who keep different Reddit accounts for different communities and want Firefox to open each subreddit in the right account automatically.

Instead of logging out and back in, the extension uses Firefox containers as the session boundary. You assign subreddits like r/privacy, r/politics, or r/gaming to specific accounts, and the extension reopens Reddit tabs in the matching account when needed.