What it is
AniBridge is a small daemon that listens for Plex playback events and syncs them to AniList. When I finish an anime episode in any Plex client (phone, TV app, browser), AniBridge tells AniList "episode N watched" and my list updates.
Why I run it
Seanime handles AniList sync when I'm watching through Seanime. But a lot of my anime watching happens through the Plex apps on the TV, where Seanime isn't running. Without AniBridge, those episodes don't get tracked.
The two services are complementary: Seanime tracks anime watched through Seanime, AniBridge tracks anime watched through Plex. They use different auth flows (Seanime is per-user OAuth, AniBridge is a server-side JWT) and don't conflict.
How I use it
Set-and-forget. It runs in the same stack as Plex, listens for webhook events from Plex, matches the show against AniList by metadata, and updates progress. The web UI exposes settings and a live activity view — useful for confirming sync is actually working and not silently broken — but day to day I don't open it.