Recommended Opera Extensions for Web Developers [Comprehensive List]

Opera desktop browser’s latest version, i.1. Opera 11 has added extensions (addon) to its feature set and interestingly, Opera 11 was downloaded 6.7 million times on the first day itself. As Opera continues to gain share in the desktop browser market, web developers cannot afford to ignore it anymore.opera_extensions

Here is presenting a set of most useful plugins for web developers and designers:

URL Encoder/Decoder

Use this extension to encode/decode URI. It is useful to encode strings the same way that the posted data from WWW forms are encoded. Non-alphanumeric characters (depending on the chosen Javascript method) are replaced with a percent sign (%) followed by two hex digits.
The following encoding/decoding methods are available on the extension preferences page:
– encodeURI / decodeURI
– encodeURIComponent / decodeURIComponent (default)
– escape / unescape


Opera’s version of MeasureIt, OMeasure! is a simple measuring tool for web developers.


Validates a page with W3C’s Validator. Pretty much a standard feature.

JSON Viewer

Formats and highlights JSON data loaded from file or server. String and Boolean values are highlighted with blue, numbers – with green, null values – with red color.

Edit the Page

Edit the page like a WYSIWYG editor. This extension toggles the ‘Design Mode’ so that you can edit the contents of the page. A great way to play/experiment with the layout, without changing any piece of code.

HTML5 Outliner

Outlines a web page’s HTML5 elementsHTML5Outliner_screenshot

Displays an outline of the current page using the HTML5 outlining algorithm. This extension is a port of the bookmarklet at


Render ruby(*) annotation (furigana and stuff)

HTML Ruby adds support for basic rendering of ruby annotation in Opera. After installation, ruby annotations in pages will be automatically processed and rendered as closely as possible to the ruby annotation spec.

*: “ruby” are small texts that are usually displayed above base texts to show the pronunciation of characters used in East Asian languages.


The extension allows to execute custom JavaScript code on any site and to store the comments for pages. JavaScript code is executed when the page loads, and can contain jQuery selectors.

Custom JavaScript code can be executed for different groups of pages:
1. For all sites
2. For all subdomains
3. For a specific domain
4. For a specific page

Snap Links

A productivity booster, this extension helps when you are researching on a topic. This extension enables you to select an area containing links and have them open all at once.


Transforms special HTML comments found in webpages you’re developing into blocks of Lorem Ipsum text.

When this extension is enabled, every webpage you view will be checked for special HTML comments that specify numbers or ranges of words, sentences, or paragraphs.

Other useful Opera extensions: WhatisMyIP, NoAds, NotScripts (to block scripts), Wayback Machine and Translate.

Also, one cannot afford to not mention the Firebug clone, i.e. DragonFly which has improved significantly since the launch and provides the much needed debugging help to web developers.

To summarize, Opera (in the current form) doesn’t boasts of the same quality (of plugins/extension) as its rival, especially Chrome and Firefox. But as the day progresses, expect this Norway based company to get more aggressive in building a developer community.

What’s your favorite Opera extension?

Also see: 30 Kickass Firefox Plugins for Web Developers

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