FileBot is the ultimate tool for organizing and renaming your movies, tv shows or anime, and music well as downloading subtitles and artwork. It's smart and just works.
Caption takes the effort out of finding and setting up the right subtitles. A simple design, drag & drop search, and automatic downloading & renaming let you just start watching. Caption is multi-platform, open-source, and built entirely on web technology.
This extension hasn't been updated since April 2017 but can still be downloaded.
Submarine is a command-line program for searching and downloading the right subtitles for movies. Subtitles are searched based on movie file hashes and downloaded from online subtitle services. Downloaded subtitles are automatically renamed and saved next to corresponding files.
Last update is from May 2012.
SubDownloader is a program for automatic find and download/upload subtitles for your movies/series (MKV,MP4,AVI,etc).Discontinued
The software hasn't been updated since 2012 but can still be downloaded.
With SubiT, you can download subtitles for your favorite movies and series by just right clicking them and executing SubiT.
The project is no longer developed. Last version, 2.2.5, released in September 2014, can be still downloaded from SourceForge and GitHub.