Aegisub

Aegisub is a free, open-source, cross-platform subtitle editing and typesetting program. It is commonly used by fansubbers and subtitlers to create and modify subtitles for video and audio files.

Aegisub is designed to be a powerful and flexible tool, offering features such as real-time video preview, waveform display for audio synchronization, advanced typesetting with ASS (Advanced SubStation Alpha) and SSA (SubStation Alpha) subtitle formats, and script automation through Lua scripting. It allows users to precisely control the timing, positioning, and styling of subtitles, enabling the creation of visually appealing and professional-looking results.

The software supports a wide range of video and audio formats through its integration with FFmpeg. Aegisub's interface includes tools for visual synchronization, allowing users to accurately adjust subtitle timings by observing the video and listening to the audio. It also features a comprehensive styling system with customizable fonts, colors, outlines, shadows, and other visual effects.

Aegisub is actively developed and maintained by a community of contributors. It is available for multiple operating systems, including Windows, macOS, and Linux. Due to its capabilities and free availability, it has become a popular tool in the fansubbing and subtitling communities.