There is JellyPlexWatch, which will sync the databases between jellyfin and Plex. I've been using both next to each other for a while with that setup to sync watch history. Honestly I haven't been able to move over to Jellyfin after the drama around the integration of skip intro, but I hope things get better.

https://github.com/luigi311/JellyPlex-Watched

> the drama around the integration of skip intro

what are you referring to?

A project to integrate additional "media segments" to identify introductions and end credits for auto-skipping.

There was something that worked, going forward the core team decided to focus on a tight stream lined core and decruft 'features'.

Discussion:

https://old.reddit.com/r/selfhosted/comments/1dbiw90/skip_in...

https://forum.jellyfin.org/t-intro-skipper-project-dead

Seems like a temporary (indefinite) suspension and a storm in a teacup from those attached to the feature.

This isn't that important a feature most of the time, because you can just press the skip-ahead button and skip the next 30 seconds. You might see some of the intro, but big deal

There is one big exception though: if you're watching Star Trek: Enterprise. The "skip intro" feature is invaluable so you don't have to be subjected to that truly horrific opening song.

More at https://news.ycombinator.com/item?id=43064585