How to contribute

This page is all about how you can contribute to VirtualBox. If you are only looking for information on how to download and run VirtualBox, see the end-user documentation page instead. If you first want to find out how to get the VirtualBox source code and build it, have a look at the technical documentation.

There are many ways how you can contribute to VirtualBox. Even if you're not a programmer, you can help us with the documentation, or work on the design, or you can help us by regularly trying out test builds - which are expected to be almost as reliable as normal releases - and telling us about any problems you encounter which were not present before.

On the other hand, if you know how to program C++, you are certainly welcome to contribute code of all sorts. For a start, we suggest you browse through our list with suggestions for contributions or take a look at past contributions.

Allowing Oracle to incorporate your contributions

Even though VirtualBox' source code is licensed to you under the GPL, it's not enough to submit your patches under the GPL. The Licensing FAQ will tell you more about how Oracle handles VirtualBox licensing.

In any event, if you like to contribute anything that is subject to copyright (text, media, or code), Oracle must be legally certain they can redistribute the code you have contributed to their own customers who have purchased closed-source editions of VirtualBox. In order to be able to accept your contribution, we must therefore ask you to do one of two things:

1. Fill out the Contributor's Agreement (CA) and send it to Oracle. With the CA, you give Oracle permission to use your contribution under licenses other than the main VirtualBox license. This is a once-in-a-lifetime event: once we have your CA, we will never again ask you to undergo any bureaucratic procedures, and all future contributions are covered.

2. If you don't want to sign such an agreement, you can alternatively submit your contribution under the UPL license or if there is no other option under the MIT license. Both are liberal, wide-spread Open Source licenses that allows Oracle (and anyone else) to use your contribution in both open-source and closed-source projects.

Basically, the main difference between the two options is this: With the CA, a written statement is necessary, but then only Oracle is allowed to relicense your code (unless you give other people the same permission). With the UPL or MIT license, you save the paperwork, but everyone else can use your code as well. It's your choice.

The VirtualBox development model

The source code of VirtualBox resides in a public Subversion repository which is hosted on this site. Currently, only Oracle employees have write access to ensure that only reviewed and tested patches find their way to the repository. However, over time, we would like to extend the group of people with write access.

Patches are always first applied to an internal Oracle repository and then automatically synchronized to the public repository. A large test laboratory at Oracle's facilities and a dedicated test team in 24/7 operation ensure that the code quality remains excellent: dozens of test machines perform automated tests to spot regressions and monitor performance.

Automated build servers for all supported platforms create ready-to-run VirtualBox installers every time changes are made to the VirtualBox source code. These development builds provide end users with the latest features but may not necessarily be well tested or stable.

In addition to development builds, we also perform regular product releases based on a milestone plan. As we work hard to produce high quality software releases, it is important for all VirtualBox contributors to respect these milestones.

How to submit your contributions

If you have developed a patch for VirtualBox which you think could be useful for others and fits within the product's architecture, then you should submit it for inclusion. As a first step, you should execute the Contributor's Agreement as described above, which is a very straightforward and risk-free process. Then you should submit your patch to the vbox-dev mailing list or to the Developers Corner forum (see the "Community" page) along with a description of what it does. In case you have not signed the CA, please explicitly state that you are licensing the patch under the MIT license.

Please keep in mind that it might take some time to review your patch and integrate it. Also, please expect feedback from other developers on how to improve your patch and address potential issues. We can only incorporate your patch if it does not harm the product stability.