Aegisub

Aegisub is a free, open-source, cross-platform subtitle editor designed for creating, modifying, and synchronizing subtitles with audio and video. It provides advanced tools for precise subtitle timing, text formatting, and visual styling. Users can synchronize dialogue with audio waveforms and spectrograms to improve accuracy. Its built-in video preview allows subtitles to be reviewed and adjusted in real time. The software supports Advanced SubStation Alpha (ASS) subtitles, enabling detailed control over fonts, colors, positioning, and effects. It also includes automation capabilities through Lua scripting for repetitive tasks and complex typesetting operations. Aegisub is particularly useful for translators, subtitlers, and video editors working on professional or fan-created subtitles.