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Pyjs is a port of Google Web Toolkit to Python, and thus enables the development of Rich Media AJAX applications in Python, with no need for special browser plugins. Pyjs contains a stand-alone python-to-javascript compiler, and also a Widget Set API that looks very similar to Desktop Widget Set APIs (such as PyQT4 or PyGTK2).

Pyjs also contains a Desktop Widget Set version, running as pure python, with three useable Desktop ports available. With web-engine technology at it's core, HTML, CSS, plugins and other related features work out-of-the-box.


Pyjs-Compiler is a collection of tools that are related to
  • compiling python code to javascript
  • linking compiled javascript modules into complete applications
  • converting java to python, etc.

Pyjs-Compiler runs your python application in a Web Browser (as javascript).


Pyjs-Widgets is a collection of GUI widget libraries that can be run natively as part of Pyjs-Native or can be compiled by Pyjs-Compiler to run in a browser.


While Pyjs runs your python application in a Web Browser (as javascript), Pyjs-Desktop runs exactly the same python application on the Desktop (as pure python). There are currently three engine choices, with alternatives in development.

All ports of Pyjs-Desktop require a JSON library; simplejson is recommended if the version of python is 2.5 or older. Python 2.6 and above come with a json library installed by default.

  1. XULRunner

    Install hulahop and python-xpcom. Hulahop, from OLPC SugarLabs, is distributed with both Debian and Ubuntu; python-xpcom is part of XULRunner and is also distributed with both Debian and Ubuntu. Other users should investigate the installation instructions for python-xpcom and hulahop for the operating system of their choice on the appropriate web sites.

    Older versions of XULRunner must be used: versions 1.9.0 or 1.9.1 are known to be suitable, as is version 9.0. Versions 10 and above are known to segfault.

  2. GIWebKit (GObject Introspection)

    A 95% functional binding enabled via the dynamic GObject/Python bindings produced by after scanning the annotated WebKit sources. This backend is missing a critical piece, window.addEventListener, from but development is in progress to implement the missing binding via ctypes instead, due to a lack of interest by WebKit.

    This is intended to supercede XULRunner as the default on Linux once ready.

    GIWebKit must be explicitly enabled. Create a $HOME/.pyjd/pyjdrc file containing the following two lines:

    [gui] engine=giwebkit


    For Windows users - all that's required, other than installing python and Internet Explorer, is one further tiny package: Win32 "comtypes".

    Win32 "comtypes" can be downloaded here: *

    Unlike the other ports, which can comprise a whopping great bundle of anything up to 30mb in size, the MSHTML port literally requires nothing more than comtypes, thanks to the far-sighted design of the MSHTML Trident Engine and its extensive COM interface.


Access our "Getting Started" wiki ( for get information about installation, examples, troubleshooting, etc.

For more information and documentation, see:

For issue tracking:

To join the mailing list: