The ones I know:

Flox - https://github.com/devfake/flox

MediaTracker - https://github.com/bonukai/MediaTracker

iwatched - https://github.com/hakanersu/iwatched

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I’ve been looking for something like this for a while !! There’s some self hosted solutions alternatives for trakt, but I don’t want the hassle… A fedi letterbox like would be really amazing! (Imagine integrating it with Jellyfin to rate your films after watching, sharing those reviews and film lists on mastodon, pixelfed and Lemmy, a dream would come true)