WebKit has had many contributions from individuals acting on their own as volunteers. There have also been numerous contributions made by people representing companies or other kinds of organizations. It is occasionally a matter of public interest which companies or groups have contributed, and to what extent
KDE is an open source desktop environment and application development framework. The project to develop this software is an informal association. WebKit was originally created based on code from KDE's KHTML and KJS libraries. Although the code has been extensively reworked since then, this provided the basic groundwork and seed code for the project. Many KDE contributors have also contributed to WebKit since it became an independent project, with plans that it would be used in KDE as well. This has included work on initially developing the Qt port, as well as developing the original code (KSVG2) that provides WebKit's SVG support, and subsequent maintenance of that code.
Apple employees have contributed the majority of work on WebKit since it became an independent project. Apple uses WebKit for Safari on Mac OS X, iPhone and Windows; on the former two it is also a system framework and used by many other applications. Apple's contribution has included extensive work on standards compliance, Web compatibility, performance, security, robustness, testing infrastructure and development of major new features.
Collabora has worked on several improvements to the Qt and GTK+ ports since 2007, including NPAPI plugins support, and general API design and implementation. Collabora currently supports the development of the GTK+ port, its adoption by GNOME projects such as Empathy, and promotes its usage in several client projects.
Nokia's involvement with the WebKit project started with a port to the S60 platform for mobile devices. The S60 port exists in a branch of the public WebKit repository along with various changes to better support mobile devices. To date it has not been merged to the mainline. However, a few changes did make it in, including support for CSS queries. In 2008, Nokia acquired Trolltech. Trolltech has an extensive history of WebKit contributions, most notably the Qt port.
Google employees have contributed code to WebKit as part of work on Chrome and Android, both originally secret projects. This has included work on portability, bug fixes, security improvements, and various other contributions.
Torch Mobile uses WebKit in the Iris Browser, and has contributed significantly to WebKit along the way. This has included portability work, bug fixes, and improvements to better support mobile devices. Torch Mobile has ported WebKit to Windows CE/Mobile, other undisclosed platforms, and maintains the QtWebKit git repository. Several long-time KHTML and WebKit contributors are employed by Torch Mobile.
Igalia is a free software consultancy company employing several core developers of the GTK+ port, with contributions including bugfixing, performance, accessibility, API design and many major features. It also provides various parts of the needed infrastructure for its day to day functioning, and is involved in the spread of WebKit among its clients and in the GNOME ecosystem, for example leading the transition of the Epiphany web browser to WebKit.
Company 100 has contributed code to WebKit as part of work on Dorothy Browser since 2009. This work includes portability, performance, bug fixes, improvements to support mobile and embedded devices. Company 100 has ported WebKit to BREW MP and other mobile platforms.
University of Szeged
Samsung has contributed code to WebKit EFL (Enlightenment Foundation Libraries) especially in the area of bug fixes, HTML5, EFL WebView, etc. Samsung is maintaining EFL buildbots and the EFL early warning system.
ProFUSION did the current EFL port of WebKit and has been working mainly on development and maintenance of this port. Major work done, apart from the initial port itself, has been on the Tiled Backing Store and Dump Render Tree implementation, as well as several bug fixes and performance improvements.
Adobe employees have contributed code to WebKit focusing on areas related to CSS layout (CSS Regions) and visual effects (CSS Shaders) as well as improvements to SVG and bug fixes.
Intel contributes code to WebKit EFL, WebCore and other parts of the WebKit code base. This includes work on new functionality as well as bug fixes. Intel is also maintaining the official EFL 64bit debug build bot.
BasysKom contributes to WebKit project with Qt-related bug fixes, platform-agnostic graphical additions and new features, like CSS3 Text Decoration.