Tabby is a terminal emulator that can be used on Windows, macOS, and Linux. It can also be used for SSH or as a serial terminal. 

It offers support for PowerShell, WSL, Git-Bash, Cygwin, MSYS2, Cmder, and CMD. It also includes an integrated encrypted container for SSH secrets and configuration. 

The project maintainers say that while it is intended as an alternative to things like Windows’ standard terminal, PowerShell, PuTTY, macOS, and iTerm, it is not intended as a MinGW or Cygwin replacement.

Features of the terminal include nested split panes, an optional dockable window, progress detection, notifications when processes are completed, and more.

SSH features include X11 and port forwarding, automatic jump host management, agent forwarding, and login scripts.

Serial terminal features include saved connections, readline input support, optional hex byte-by-byte input and hexdump output, and more. 

It is highly customizable to user preferences, with theming and color scheme options and fully configurable shortcuts.