About Safari Extensions
Safari extensions provide a way for you to add features to the Safari browser. You can add custom buttons to the Safari toolbar, create bars of your own, add contextual menu items, display content in bars or tabs, and inject scripts and style sheets into webpages. In Safari 5.1 and later, you can add menus and popovers to toolbar items.
Safari extensions are supported in Safari 5.0 and later on the desktop (Mac and Windows). Safari extensions are not currently supported on iOS.
At a Glance
Safari extensions let you add persistent items to Safari—controls, menus and menu items, local or web-based content, and scripts that modify the content Safari presents.
What’s the Difference Between an Extension and a Plug-in?
A plug-in can add support for media types to a browser. An extension can add many different features.
Extensions and plug-ins both expand a browser’s capabilities. Plug-ins let browsers display media that the browser can’t display natively or provide a particular media player experience. Extensions personalize and enhance the browser itself and can interact with HTML web content.
A plug-in can’t interact with webpages except to display media of specific MIME types. A plug-in cannot add features to Safari, such as toolbar buttons or contextual menu items.
A plug-in is a binary file that interfaces with the browser but is essentially an app in itself—the browser hands off specific media types to the plug-in to handle.
Extensions Run in a Sandbox
You Create Extensions Right in Safari
The main ingredients of an extension are:
Global HTML page—code that’s loaded once, when Safari launches or when your extension is enabled. This is the ideal place to put the code for buttons in the Safari toolbar, extension menus, or contextual menus. This page is never displayed; it’s just for logic.
Menu Items (labels, images)—items that appear in extension menus that you define, or are added to Safari’s existing contextual menus.
Injected scripts—scripts to be injected into browser content. These scripts can read, modify, add to, or delete content.
Injected style sheets—user style sheets that can modify the display of web content by overriding or adding to the styles normally applied.
Icon image—the icon for your extension.
You Can Define User Settings in Extension Builder
Your extension can have its own user settings, accessible to the user in the Extensions pane of Safari preferences. You define the settings, user interface items, and default values using Extension Builder.
There is also a settings API similar to HTML5 local storage for accessing and modifying settings programmatically. You can use encrypted settings for security.
Debug Your Extension with Safari’s Built-in Tools
Update Your Extension Automatically from the Web
Safari provides a method to support checking for updates to an extension automatically: the Update Manifest. You specify a web address, and Safari periodically compares the installed version of your extension with the latest version on your website. If your website has a newer version, Safari offers the user an update.
Safari Web Inspector Guide—the built-in web development tools that come with Safari.
Safari Extensions Conversion Guide—a guide to converting extensions written for other browsers.