Subtitle Workshop is an application to add, edit and convert subtitles. It's as easy as typing when using a text edition tool and set the timing.
It allows you to preview subtitles, so you can edit them perfectly and check if the position and timing is perfect.
Subtitles can be saved and imported as and from many different formats including .ass, .aqt, .txt, .asc, .dks, .sub, .mpl, .psb, .smi, .stl, .vsf, .zeg, and more.