I wrote a script to auto-rename messy media files when moving from Plex to Jellyfin
If you're jumping to Jellyfin, you've probably got a library full of files like "the-matrix-1999-1080p-x264.mkv" that don't scan in cleanly. I got tired of renaming stuff by hand, so I wrote a script that pulls the correct titles/years/episodes straight from Plex and renames the files to match: "The Matrix (1999).mkv", "Game of Thrones (2011) - S01E01 - Winter Is Coming.mkv", that kind of thing.
Nothing changes until you review the list and confirm (there's a --dry-run too), and every run leaves an undo file just in case. It can also restructure folders into Jellyfin's preferred layout, and optionally bring over your watched status/ratings from Plex.
It's just a Python script, with one dependency. Thought I would share it in case the script saves someone else effort. I'd be happy to help if anyone hits issues with it.
Just a disclaimer, I have used this myself and it worked perfectly for me, but even though it has an undo scrip built right in, I can not guarantee that it will work perfectly for you. However, please use at your own risk. If anyone runs into problems, I would be happy to help.
Here is the link to the GitHub page where you can download it: https://github.com/Mumbolio85/Plex-File-Rename