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Quasar is a cross-platform desktop application that displays web-based widgets on your desktop. Quasar leverages the Chromium engine to serve desktop widgets in a platform agnostic manner. Widgets can be as simple as a single webpage with a couple of lines of HTML, a complex fully dynamic web app, or even a WebGL app.

Quasar provides a WebSocket-based Data Server that is extensible by custom extensions. The Data Server is capable of processing and sending data to client widgets that would otherwise not be available in a purely web-based context, for example, your PC’s resource information such as CPU and memory usage, or your Spotify client’s now-playing information.

See Creating an Extension Quickstart and Extension API Reference for more information on how to create a Data Server extension, and Creating a Widget for building widgets.

Quasar is licensed under GPL-3.0. All sample widgets are licensed under the MIT license.

System Requirements

An OS and computer capable of running Chrome, preferably with Hardware Acceleration capabilities. Only 64-bit OSes are supported. On Windows, only Windows 10 and above are supported. On Linux, only X11 desktop environments with system tray support are supported.

While Quasar is reasonably fast and lightweight, do not expect Quasar to be power efficient, especially when running heavier widgets like the WebGL visualizer.

Note Regarding Wayland

Quasar does not work properly on Wayland compositors due to Wayland not supporting functions like global cursor position or explicitly setting window positions for top-level windows [1] [2], which completely defeats Quasar’s core functionality. Until a workaround or solution is added to Qt itself, Quasar cannot support Wayland.

Qt on Linux

Quasar has been built and tested on the latest pre-built binaries supplied by Qt, which at the time of writing is Qt 6.4.2 built against OpenSSL 1.1.1. The Qt version offered by Ubuntu 22.04’s package repository is Qt 6.2.4 built against OpenSSL 3.0. As of Ubuntu 22.04, OpenSSL 3 is the default and version 1.1.1 is no longer offered in the package repository. Building Quasar on versions of Qt older than 6.4 may work but is not supported. Ensure that the version of the OpenSSL libraries installed (i.e libcrypto.so and libssl.so) matches the version your Qt installation is built against or SSL functionality will fail.

Getting Started

Download the latest portable release here, for Windows x64.

Simply extract Quasar and run the application.

The Quasar icon will then show up in your desktop’s notification bar. Right-click the icon, load your desired widgets, and enjoy! See Basic Usage for more details.

Creating Widgets/Extensions

See Creating an Extension Quickstart and Extension API Reference for more information on how to create a Data Server extension, and Creating a Widget for building widgets.

Building Requirements

Source code is available on GitHub.

  • CMake 3.23 or later

  • Qt 6.4 or later, with at least the following additional libraries:

    • WebEngine (qtwebengine)

    • Positioning (qtpositioning)

    • WebChannel (qtwebchannel)

    • Network Authorization (qtnetworkauth)

    • Serial Port (qtserialport)

  • The Qt6_DIR environment variable defined for your Qt installation

    • Windows example: C:\Qt\6.4.2\msvc2019_64

    • Linux example: $HOME/Qt/6.4.2/gcc_64/

    • On Linux, additional dependencies may be needed for Qt such as the packages libgl1-mesa-dev libglvnd-dev

  • Visual Studio 2022 or later is required

  • Clang (or the Clang MSVC toolkit in Visual Studio) is required if you wish to build the win_audio_viz sample extension

  • gcc/g++ 11 or later, or Clang 16 or later

    • Tested on Ubuntu 22.04 using both g++ 11 and 12

    • Clang 15 and earlier fails to compile gcc’s implementation of the C++20 ranges library, which is used in Quasar

  • Clang is required if you wish to build the pulse_viz sample extension

  • vcpkg dependencies, for example including but not limited to the following Debian-based packages:

    • build-essential tar curl zip unzip pkg-config

Quasar is written in cross-platform C++ and should build on Mac with minimal changes. However, it is currently untested and unsupported.

git clone --recurse-submodules https://github.com/r52/quasar.git
cd quasar


The following example configures the project to build using the clang-cl toolkit with Visual Studio Community 2022 (plus the Clang MSVC toolkit) installed:

cmake --no-warn-unused-cli -DCMAKE_EXPORT_COMPILE_COMMANDS:BOOL=TRUE "-DCMAKE_C_COMPILER:FILEPATH=C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\Llvm\x64\bin\clang-cl.exe" "-DCMAKE_CXX_COMPILER:FILEPATH=C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\Llvm\x64\bin\clang-cl.exe" -S./ -B./build -G "Visual Studio 17 2022" -T ClangCL,host=x64 -A x64


The following example configures the project to build using g++-12, assuming g++ 12 is installed, and configures Quasar to be installed to $HOME/.local/quasar/:

export CC=gcc-12
export CXX=g++-12
cmake --no-warn-unused-cli -DCMAKE_EXPORT_COMPILE_COMMANDS:BOOL=TRUE --install-prefix $HOME/.local/ -S./ -B./build -G "Unix Makefiles"

-G Ninja can also be used provided that Ninja is installed.

Building the Project

cmake --build ./build --config Release --

Installing from Build (optional)

cmake --install ./build


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