Documentation for Opera 11 & 12 extensions

By Andreas Bovens

With Opera switching from Presto to Chromium and a complete UI remake, our extensions infrastructure has also gotten a major overhaul: from Opera 15 onward, Opera 11 & 12’s extension format is no longer supported, and instead, we’ve switched to Chromium’s extension model. Check out our new documentation for developing extensions for Opera 15 and higher and start building your own extensions.

Getting started

• Saying hello world to Opera extensions
• What’s in an Opera extension?
• Opera extensions developer workflow

API reference

You can build Opera extensions using the Opera Extensions APIs and open web standards like JavaScript and HTML. This makes Opera extensions easy to create, quick to debug, and fast to install.

Basics and UI elements:

• config.xml (defining the extension)
• Metadata and preferences
• Button and badge
• Popup window
• Windows & Tabs

Browser functions:

• Injected scripts (add JavaScript to websites)
• URL filtering (e.g. for ad blocking)
• Messaging (e.g. between the background process and the injected script)
• Speed Dial (for Speed Dial extensions)
• Resource Loader (access any file within an extension package)
• Screenshot (take screenshots of pages)
• Context Menu (add items to the context menu)

Finishing up:

• Adding an options page
• Packaging your extension
• Publishing it to the Opera extensions catalog

Extension tutorials

• The ins and outs of config.xml
• Buttons, badges and popups
• Messaging
• Options page
• Accessing an Opera extension's background process
• Creating Opera Speed Dial extensions
• Cookie-sharing in Opera extensions
• Site blocking with Opera’s URL Filter API
• Creating multilingual extensions
• Hands-on tutorial: building an Opera extension
• Converting UserJS to Opera extensions
• Converting widgets to Opera extensions: Things to keep in mind

Templates and code samples

• Opera extension code examples
• Opera extensions prototypes for modifying CSS
• Speed Dial extension boilerplate (Github)
• Turn your RSS into a live Opera Speed Dial extension

UI guidelines and distribution

• Publishing guidelines
• Creating effective Opera Extension icons
• Distributing Opera extensions and auto-updates

Andreas Bovens

Andreas is based in Oslo, where he works for Opera Software as Extensions Product Manager + Developer Relations.

This article is licensed under a Creative Commons Attribution 3.0 Unported license.