WebKit is a cross-platform web browser engine. On iOS and macOS, it powers Safari, Mail, Apple Books, and many other applications. For more information about WebKit, see the WebKit project website.

On macOS, download Safari Technology Preview to test the latest version of WebKit. On Linux, download Epiphany Technology Preview. On Windows, you'll have to build it yourself.

1. Search WebKit Bugzilla to see if there is an existing report for the bug you've encountered.
2. Create a Bugzilla account to report bugs (and comment on them) if you haven't done so already.
3. File a bug in accordance with our guidelines.

Once your bug is filed, you will receive email when it is updated at each stage in the bug life cycle. After the bug is considered fixed, you may be asked to download the latest nightly and confirm that the fix works for you.

Run the following command to clone WebKit's Git repository:

git clone https://github.com/WebKit/WebKit.git WebKit

You can enable git fsmonitor to make many git commands faster (such as git status) with git config core.fsmonitor true

Install Xcode and its command line tools if you haven't done so already:

1. Install Xcode Get Xcode from https://developer.apple.com/downloads. To build WebKit for OS X, Xcode 5.1.1 or later is required. To build WebKit for iOS Simulator, Xcode 7 or later is required.
2. Install the Xcode Command Line Tools In Terminal, run the command: xcode-select --install

Run the following command to build a macOS debug build with debugging symbols and assertions:

Tools/Scripts/build-webkit --debug

For performance testing, and other purposes, use --release instead.

To build for an embedded platform like iOS, tvOS, or watchOS, pass a platform argument to build-webkit.

For example, to build a debug build with debugging symbols and assertions for embedded simulators:

Tools/Scripts/build-webkit --debug --<platform>-simulator

or embedded devices:

Tools/Scripts/build-webkit --debug --<platform>-device

where platform is ios, tvos or watchos.

You can open WebKit.xcworkspace to build and debug WebKit within Xcode. Select the "Everything up to WebKit + Tools" scheme to build the entire project.

If you don't use a custom build location in Xcode preferences, you have to update the workspace settings to use WebKitBuild directory. In menu bar, choose File > Workspace Settings, then click the Advanced button, select "Custom", "Relative to Workspace", and enter WebKitBuild for both Products and Intermediates.

For production builds:

cmake -DPORT=GTK -DCMAKE_BUILD_TYPE=RelWithDebInfo -GNinja
ninja
sudo ninja install

For development builds:

Tools/gtk/install-dependencies
Tools/Scripts/update-webkitgtk-libs
Tools/Scripts/build-webkit --gtk --debug

For more information on building WebKitGTK, see the wiki page.

For production builds:

cmake -DPORT=WPE -DCMAKE_BUILD_TYPE=RelWithDebInfo -GNinja
ninja
sudo ninja install

For development builds:

Tools/wpe/install-dependencies
Tools/Scripts/update-webkitwpe-libs
Tools/Scripts/build-webkit --wpe --debug

For building WebKit on Windows, see the WebKit on Windows page.

Run the following command to launch Safari with your local build of WebKit:

Tools/Scripts/run-safari --debug

The run-safari script sets the DYLD_FRAMEWORK_PATH environment variable to point to your build products, and then launches /Applications/Safari.app. DYLD_FRAMEWORK_PATH tells the system loader to prefer your build products over the frameworks installed in /System/Library/Frameworks.

To run other applications with your local build of WebKit, run the following command:

Tools/Scripts/run-webkit-app <application-path>

Run the following command to launch iOS simulator with your local build of WebKit:

run-safari --debug --ios-simulator

In both cases, if you have built release builds instead, use --release instead of --debug.

To run other applications, for example MobileMiniBrowser, with your local build of WebKit, run the following command:

Tools/Scripts/run-webkit-app --debug --iphone-simulator <application-path>

Open WebKit.xcworkspace, select intended scheme such as MobileMiniBrowser and an iOS simulator as target, click run.

If you have a development build, you can use the run-minibrowser script, e.g.:

run-minibrowser --debug --wpe

Pass one of --gtk, --jsc-only, or --wpe to indicate the port to use.

Congratulations! You’re up and running. Now you can begin coding in WebKit and contribute your fixes and new features to the project. For details on submitting your code to the project, read Contributing Code.