Subtitle Edit

Subtitle Edit (also known as SE) is a free and open-source subtitle editor to create, edit, adjust or synchronize subtitles for videos.
Features.
SE supports 250+ subtitle formats. Some of the most popular ones are SubRip, Timed Text, DFXP (Netflix standards), ITT (iTunes), SubStation Alpha, MicroDVD, SAMI, D-Cinema and BdSub. It uses the VLC media player, MPC-HC, Mpv or DirectShow to play videos.
It is available in 34 languages and works on Windows and Linux.
Development.
In 2001 Nikolaj Lynge Olsson had started the development on Subtitle Edit in Delphi which continued until April 2009. On 6 March 2009, 2.0 Beta 1 version (build 42401) was released.
Over time, more developers have contributed to SE's development and it is still active. It is hosted at GitHub.
On May 17, 2011 the developer announced the testing version of SE 3.2 for Linux. It uses the same source code that was developed for Windows, to implement it on Linux using Mono Project.
On October 17, 2011 the developer announced the availability of stable version for Linux. The developer himself stated that it is working well on Ubuntu.