Free tool
Open two .srt files for the same film, one in each language, and save one subtitle that shows both, one line above the other. Plex, VLC and any other player show it as a normal subtitle. It all happens in your browser, and the files never leave your computer.
Each line of the bottom language goes under the line of the top one it overlaps most, and each language is kept to one line on screen. A line with nothing to pair with stays on its own. Both files need to be timed for the same release. If one runs early or late, fix its timing first.
Save it next to the film with the same name and the top language's code, like Amélie (2001).fr.srt. Plex lists it under that language in the subtitle menu.
Pick two languages on a film in StreamBridge Pro and both appear in Plex, one above the other. It finds a subtitle in each language for your release, times them against the film's audio, and translates when one language doesn't have a subtitle. How it works →