An i3/Sway utility to switch focus to your last focused window. Allows for behavior similar to Alt+Tab on other desktop environments.

Features:

• Can switch between your 2 most recent windows
  • Runs a daemon (background process) to listen for focus changes and sets a mark
• Supports i3 and Sway
• Supports floating windows
• Can be binded to any key through i3's bindsym

i3-back requires i3/Sway. It is written in Rust. It can be installed through many method:

• Cargo (Rust's package manager) package:

  cargo +nightly install i3-back
  

• Arch Linux from the AUR (i3-back-bin):

  yay -S i3-back-bin # Or with paru or other AUR wrappers
  # Or manually: https://wiki.archlinux.org/title/Arch_User_Repository#Installing_and_upgrading_packages
  

• Debian/Ubuntu as a deb from GitHub releases

• Binary from GitHub releases

In your i3/Sway configuration (~/.config/i3/config/~/.config/sway/config):

# Start the daemon which listens to focus changes and sets _back mark
exec --no-startup-id ~/.cargo/bin/i3-back
# Bind a switch key, which focuses the previously focused window
bindsym $mod+Tab [con_mark=_back] focus

Replace ~/.cargo/bin with wherever the i3-back binary is placed if not installed through Cargo.

All options are optional. Options are passed to i3-back as flags.

Example exec with options:

exec --no-startup-id ~/.cargo/bin/i3-back --debug --mark _last

Available options:

• --help/-h: See help text. Also see --version
• --mark <MARK>/-m <MARK>: Change the default _back mark name. Make sure to update your switcher bind's con_mark to match
• --debug/-d: Print extra debugging information

Example i3-back --help:

An i3/Sway utility to switch focus to your last focused window. Allows for behavior similar to Alt+Tab on other desktop environments.
Usage: i3-back [OPTIONS]
Options:
 -m, --mark <MARK> Change the name of the mark to set [default: _back]
 -d, --debug Print extra debugging information
 -h, --help Print help
 -V, --version Print version

The daemon (i3-back) listen for i3 window events (through i3's socket, from the I3SOCK environment variable). When a window event is received, i3-back records the previously focused window ID. When the previous focus has changed, it sets the _back mark (or whichever is configured through the --mark flag) to the last focused window.

When the switch bind is called (through i3's bindsym), it focuses the mark set by the daemon.

• @nicarran's snippet
• @lbonn's i3-focus-last