Aegisub is a free and open source subtitle editor application for Linux, Windows and MacOS. Using Aegisub, you can create and modify subtitles easily. It comes with built-in real-time video preview, many formats and character sets support, visual typesetting tools, customizable audio timing mode, scriptable automation module and many more.
Download Aegisub [Windows, MacOS]
How to Install Aegisub on Ubuntu
Aegisub is available as a flatpak package file from the remote flathub. First install flatpak and flathub using blow link and restart your system after the installation.
How to Install Flatpak and flathub
In the terminal application (ctrl+alt+t) run below Aegisub flatpak install command.
flatpak install flathub org.aegisub.Aegisub
It will install the latest Aegisub on your system. Then run below command to open it.
flatpak run org.aegisub.Aegisub
And uninstall Aegisub using below commands.
flatpak uninstall org.aegisub.Aegisub
[OR]
sudo flatpak uninstall org.aegisub.Aegisub