LAYOUT ENGINES (Rendering Engines)

Most common Layout Engines Below


Trident also known as MSHTML is the layout engine for the Microsoft Windows version of Internet Explorer.

It was first introduced with the release of Internet Explorer version 4.0 in October 1997; it has been steadily upgraded and remains in use today. For versions 7 and 8 of Internet Explorer, Microsoft made significant changes to the Trident layout engine to improve compliance with web standards and add support for new technologies. With version 9 of Internet Explorer, Microsoft intends to comply with many modern web standards, and also intends to significantly update the layout engine to be more competitive and modern compared to other current layout engines.


Tasman was a layout engine developed by Microsoft for inclusion in the Macintosh version of Internet Explorer 5. Tasman was an attempt to improve support for web standards, as defined by the World Wide Web Consortium. At the time of its release, Tasman was seen as the layout engine with the best support for web standards such as HTML and CSS. Internet Explorer for Mac is no longer supported, but newer versions of Tasman are incorporated in some other Microsoft products.


Gecko is a free and open source layout engine used in many applications developed by Mozilla Foundation and the Mozilla Corporation notably the Firefox web browser, as well as in many other open source software projects.

It is designed to support open Internet standards, and is used by different applications to display web pages and, in some cases, an application’s user interface itself by rendering XUL. Gecko offers a rich programming API that makes it suitable for a wide variety of roles in Internet-enabled applications, such as web browsers, content presentation, and client/server.

Gecko is written in C++ and is cross-platform, and runs on various operating systems including BSDs, Linux, Mac OS X, Solaris, OS/2, AIX, OpenVMS, and Microsoft Windows. Its development is now overseen by the Mozilla Foundation and is licensed by a tri-license of the Mozilla Public License (MPL), GNU General Public License (GPL) and GNU Lesser General Public License (LGPL).

Gecko is the third most-common layout engine on the World Wide Web, after Trident used by Internet Explorer for Windows since version 4 and WebKit used by Safari and Google Chrome, and followed by Presto used by Opera.


KHTML is the HTML layout engine developed by the KDE project. It is the engine used by the Konqueror web browser. A forked version of KHTML called WebKit is used by several web browsers, among them Safari and Google Chrome. Distributed under the terms of the GNU Lesser General Public License, KHTML is free software.

Built on the KPart framework and written in C++, KHTML has relatively good support for Web standards. To render as many pages as possible, some extra abilities and quirks from Internet Explorer are also supported, even though those are non-standard.


WebKit is a layout engine designed to allow web browsers to render web pages. WebKit powers the Apple Safari and Google Chrome browsers. As of 2012 it has the most market share of any layout engine at 36% of the browser market share according to StatCounter.  It is also used as the basis for the experimental browser included with the Amazon Kindle ebook reader, as well as the default browser in the iOS, Android, BlackBerry Tablet OS and webOS mobile operating systems. The WebKit engine provides a set of classes to display web content in windows, and implements browser features such as following links when clicked by the user, managing a back-forward list, and managing a history of pages recently visited.

WebKit’s HTML and JavaScript code originally began as a fork of the KHTML and KJS libraries from KDE, and has now been further developed by individuals from KDE, Apple Inc., Nokia, Google, Bitstream, RIM, Samsung, Igalia, and others. Mac OS X, Windows, GNU/Linux, and some other Unix-like operating systems are supported by the project.

WebKit’s WebCore and JavaScriptCore components are available under the GNU Lesser General Public License, and the rest of WebKit is available under a BSD-form license.


Presto is the layout engine for later versions of the Opera web browser developed by Opera Software. After several public betas and technical previews, it was released on January 28, 2003 in Opera 7 for Windows, and as of Opera 11 it is still in use. Presto is dynamic: the page or parts of it can be re-rendered in response to DOM and script events. Presto is available only as a part of Opera browser or related products; the source or binary (DLL) forms of the engine are not publicly available. Subsequent releases have seen a number of bugs fixed and optimisations to improve the speed of the ECMAScript (JavaScript) engine.