Frequently Asked Questions


  • What is OpenLaszlo?

    OpenLaszlo is an open-source platform for the development and delivery of rich Internet applications on the World Wide Web. The OpenLaszlo platform consists of three main components:

    • The OpenLaszlo compiler takes an OpenLaszlo source files and compiles it into a Flash or DHTML file that runs in any browser.
    • The OpenLaszlo Runtime Framework includes user interface components, data binding, and network services.
    • The OpenLaszlo Servlet enables runtime support for additional media types and for SOAP and XML-RPC.

    With OpenLaszlo, you can:

    • Develop standards-based rich Internet applications with one code base in XML and JavaScript
    • Deploy them from any browser in SOLO mode
    • Display them in any Web browser enabled with the Flash 7 Player or above or deploy them as DHTML and require no plugins.

    Since 2002, Laszlo applications have demonstrated proven usability, scalability and reliability in public Web deployments to millions of users.
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  • When and why did OpenLaszlo become open-sourced?

    Beginning with Version 2.2 on October 5, 2004, the entire OpenLaszlo platform, previously referred to as the Laszlo Presentation Server (LPS), was open sourced by the original developer, Laszlo Systems, to establish a free and open platform for rich client application development and deployment.

    By adopting the open source development model, we expect to accelerate the adoption of rich client applications on the open Web, as well as enhance the quality, performance and feature set of the OpenLaszlo platform. Laszlo Systems will continue to develop the open source platform, along with providing commercial application modules, support and education programs for customers.
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  • Where can I download OpenLaszlo?

    Get the current release to use or download the source to work with and extend the Laszlo platform..

  • What resources are available to learn more about OpenLaszlo?
    • Take a look at our Getting Started page for tutorials and documentation aimed at the new user.
    • Documentation is included with the binary distribution, and viewable online as well.
    • An active developer forum: Laszlo Developer Forums
    • is a great resource of simple Laszlo applications designed to be embedded in websites and blogs. You can download the source for the "Bloxes"freely.

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  • How can I contribute to the OpenLaszlo project?

    Check out our Community page for information on how to submit bugs and patches and see other ways you can get involved in OpenLaszlo

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  • What open source license is OpenLaszlo available under?

    The OpenLaszlo platform is released under the OSI-certified Common Public License (CPL 1.0). OpenLaszlo uses the CPL without modification. IBM authored this license for general-purpose use by other companies wishing to release their products under an open source license.

    The Common Public License is a 'reciprocal' license that provides maximum flexibility for commercial reuse of source code, aims to protect users against broad liability claims, and requires that modifications to the source be made available under terms compatible with this license.

    Laszlo Systems chose the CPL because it is a simple, clear and well-written license that allows customers great flexibility in building on the OpenLaszlo platform, such as permitting proprietary applications written using OpenLaszlo to remain proprietary, but ensures that any contributions to the OpenLaszlo platform itself remain open source and are "given back" to the open source community.

    For more information, see IBM's CPL FAQ.
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  • What am I allowed to do with code covered under this license?

    There is a lot you can do, from distributing the code to building your own commercial applications. Here are some examples to provide a general guideline:

    • If you choose to distribute the OpenLaszlo platform, whether commercial or free, as object code with or without any changes or additions, then you must release it under a license that complies with the CPL and must make the source code available to others.
    • If you distribute the OpenLaszlo platform, whether commercial or free, as source code with or without any changes or additions you must release it under the CPL.
    • Lastly, if you distribute the OpenLaszlo platform with a separate module of software (not a derivative work), you must license the OpenLaszlo platform under a license that complies with the CPL (if distributed as object code) or under the CPL (if distributed as source code). You may license your separate module of software (which is not a derivative work) under any license you choose.

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  • What happens if I make a modification to the platform under the CPL but choose not to distribute it to anyone else?

    Under the CPL, in this circumstance you do not need to make the source code available to others.
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  • What am I not allowed to do with code covered under this license?

    You may not make changes or additions to the OpenLaszlo platform and distribute them under a license that does not meet the requirements of the CPL.
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  • Can I sell new OpenLaszlo modules or extensions that I create?

    Yes, separate modules of software that are not derivative works of the OpenLaszlo platform can be distributed with the OpenLaszlo platform and be licensed under any terms and conditions you choose, including proprietary closed source distribution. However, you must still distribute the OpenLaszlo platform under the CPL requirements.

    We consider a new application written in LZX a separate module of software that may be licensed as you choose. However, a modification to one of the sample applications distributed with the OpenLaszlo platform is not a separate module of software and must be licensed under the CPL.
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  • Can I charge a fee for providing a hosted version of the OpenLaszlo Server?

    Yes, the CPL license permits you to do that. We encourage hosting providers or ASP vendors to utilize Laszlo Support Services in order to provide the best possible service to their customers.
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