Users can import video clips to the intuitive interface by drag-&-drop, and begin to add a mountain of subtitles to their wanted frames firsthand. The subtitles can be put and removed anywhere under the multi-track subtitling timeline at the same time. Surprisingly, TunesKit Subtitle Editor gives you a quick, free way to search for off-the-shelf video subtitles of some movies and episodes online and adds them to edit directly. On top of that, there is a quick-and-dirty one-click text inputting and encoding box for time-saving.

Add subtitles to any type of video format like MP4, AVI, WMV, etc.
Customize subtitle font, color, size, opacity, and background
Unlimited tracks for batch subtitles under the sleek interface
Real-time preview of subtitle addition and genre adjustment
Multi-language systems for short clips, movies, ads, and explainers
Auto Text-to-Subtitle feature to produce your subtitles in bulk

Jubler is a tool to edit text-based subtitles. It can be used as an authoring software for new subtitles or as a tool to convert, transform, correct and refine existing subtitles. The most popular subtitle formats can be used. Preview of the subtitles in realtime or in design time, spell checking, translation mode and styles editing are some of the main features.

Features
It supports Advanced SubStation, SubStation Alpha, SubRip. SubViewer (1 and 2), MicroDVD, MPL2 and Spruce DVD Maestro file formats, although it is easy to extend it to support other file types.
All encodings supported by Java platform are also supported here (like UTF-8). The user is able to select a list of preferred encodings in order to load the localized subtitle files.
GUI internationalization support through gettext utilities.
Styles are supported (when saving in SubStation formats). These styles are specific per subtitle or per character.
Translating mode (parent & child editors) is supported
Graphical preview of the subtitles using the FFMPEG library. Current frame, waveform preview and waveform listening is supported.

Subtitle Edit (SE) is an editor for video subtitles - a powerful subtitle editor. With SE you can easily adjust a subtitle if it is out of sync with the video and much more. For a list of features see below or check out the Subtitle Edit Help page. Also, you can watch a few videos about installing and using Subtitle Edit. Dny238 has written a nice tutorial about Syncing Subtitles with Subtitle Edit :).