This provides a simple framework to localise extensions, building on things developers already know. It is also easy to port User JavaScript to extensions, although there is of course more functionality available to make extensions more powerful. Making it easy to port extensions across platforms was a design goal. The architecture is conceptually similar to Firefox's Jetpack or the Chrome extension framework. Opera extensions also make use of new HTML5 technology such as cross-document messaging. This means that if you can write a Web application or Widget you already have the skills you need to write extensions. Our extensions framework is built on existing standards, with Widgets and JavaScript as the basis. Examples include Mapsearch, which allows you to select any address and plot it straight onto a Google Map, and Slashdotty, which allows anyone to show and hide blocks in the Slashdot UI, not just registered members. Opera extensions are packages that add extra functionality to Opera Desktop. New in Opera 11 alpha, we've added our own extensions. We want to be certain our framework doesn't impact the browser's performance, and allows for the long tail of user requirements and developer needs. We've also spent a long time looking at how to make a more powerful secure extension framework. You can modify the UI with custom icons, buttons and menu options you can write user stylesheets and User JavaScript to add custom styles and behaviour to any site you access you can also create Opera Widgets and Unite applications to provide standalone native applications written using open standards, and much, much more.

Opera has always been known for its adaptability, and wealth of options for customisation.

How to get all opera extensions