Aegisub is a free open-source cross-platform subtitle editing program. It is extensively used in fansubbing, the practice of creating or translating unofficial, noncommercial subtitles for visual media by fans.
License: Open Source
Aegisub is a powerful tool favored by advanced users for its extensive editing capabilities and customization options, especially in timed subtitles and karaoke effects. In contrast, Subtitle Edit is more user-friendly, making it ideal for beginners and offers features like spell checking and automatic timing, though it lacks some of the advanced tools present in Aegisub.