A lightning fast Alt+Tab switcher for X11 written in Zig using Raylib.

How It Works

• Press Alt+Tab to switch between all windows
• Press Win+Tab to switch between windows of the same application (e.g. all Chrome windows)
• Press Tab to move to the next window
  • Hold Shift while pressing Tab to navigate backwards
  • Or quick tap the Shift key to move backwards
  • Or navigate using the arrow keys!
  • Or click on a window with the mouse!
  • And yes, keyboard takes precedence over the mouse, unlike some other switcher 🤫
• Release Alt or Win/Super to confirm the switch

Features

• Instant window switching, no more waiting for the switcher to appear
• UI with window thumbnails, titles, and icons
• Smooth OpenGL rendering of the switcher UI
• Lightweight daemon with low CPU and memory usage

Motivation

I love my KDE Plasma desktop environment, but I find the default "Thumbnail Grid" switcher to be a bit too slow for my taste: sometimes it would take up to a second to appear, which is too long when you want to quickly switch between windows.

I believe this is because the default switcher has a major performance compromise: it generates window thumbnails on the fly when the switcher is invoked. This does make sense normally because it means that you're not wasting resources generating thumbnails for windows you might never switch to. And most likely, lots of users don't use Alt+Tab that often.

I am, however, in the opposite camp: I Alt+Tab all the time, my computer can handle the extra cpu (very little) and memory (some) no problem, and even a slight delay irritates me.

So I decided to try out writing my own Alt+Tab switcher.

FastTab improves performance in several ways:

• It runs as a daemon in the background, constantly monitoring windows and maintaining live thumbnails.
• It uses OpenGL via Raylib for fast rendering of the switcher UI
• Window thumbnails are rendered entirely on the GPU using GLX texture binding (zero-copy, no CPU overhead).
• Live thumbnail updates reflect window content changes in real-time without capturing screenshots.
• It's written in Zig!

Prerequisites

• An X11-based desktop environment (e.g. KDE Plasma, Xfce, etc)
• Hardware-accelerated OpenGL support
• Rebind the default Alt+Tab shortcuts to something else (e.g. Ctrl+Meta+Tab, Ctrl+Meta+Shift+Tab), to avoid conflicts.
• To use Win+Tab (same-app switcher): disable any desktop-environment shortcut that uses Super+Tab (e.g. in KDE Plasma: System Settings → Shortcuts → KWin → Walk Through Windows of Current Application).

Build instructions

1. Make sure you have Zig installed (version 0.14.0 or later)

2. You will also need the following development packages installed:

   • libasound2-dev
   • libgl1-mesa-dev
   • libglu1-mesa-dev
   • libwayland-dev
   • libx11-dev
   • libx11-xcb-dev
   • libxcb-composite0-dev
   • libxcb-damage0-dev
   • libxcb-image0-dev
   • libxcb-keysyms1-dev
   • libxcb-shm0-dev
   • libxcb-util0-dev
   • libxcb1-dev
   • libxcursor-dev
   • libxi-dev
   • libxinerama-dev
   • libxkbcommon-dev
   • libxrandr-dev
   • libglfw3-dev
   • libxcb-keysyms1-dev

   On Debian/Ubuntu, you can install them with sudo apt install <package-names>.

3. Clone this repository

4. Run the setup.sh script to install Raylib and other dependencies

5. Build the project with zig build -Drelease-safe

6. The resulting binary will be located at ./zig-out/bin/fasttab

Installation instructions

1. Follow the build instructions to build the project, or grab the latest binary from the releases page
2. Move the binary somewhere in your PATH (e.g. /usr/local/bin)
3. Run fasttab daemon & to start the daemon in the background
4. You're done! Try Alt+Tabbing around!

⚠️ DISCLAIMERS

• Consider this Very Beta. It works for me, but your mileage may vary.
• Yes I did use AI to help me write a lot of this code. On one hand I would have preferred to write it all myself, but on the other hand I would not have been able to finish it in a reasonable amount of time. So here we are.