Extensions: Web Development, top rated

OMeasure!

(74) by michalborek · 69,013 downloads

Simple measuring tool for web developers.

Edit the Page

(71) by shwetankdixit · 52,793 downloads

Edit the page like a WYSIWYG editor

The Developer Briefcase

(41) by shwetankdixit · 67,061 downloads

Various tools to help web developers and designers.

PageRank

(34) by inBusteR · 32,152 downloads

Alexa and Google PageRank extension for Opera

HTML5-powered

(33) by tagawa · 22,803 downloads

Displays the "HTML5-powered" icon at the top right of HTML5 pages.

JsonViewer

(33) by s-a-s-h · 17,284 downloads

Formats and highlights JSON data loaded from file or server.

Include CSS

(31) by faqfaqfaq · 15,726 downloads

Extension that allows developers to include multiple CSS stylesheets on any visited website. It features 'CSS autorefresh' (for live editing with your favourite IDE) and…

WebMoney Advisor

(26) by aorkne · 277,586 downloads

Internet users feedback about the sites

Readable JavaScript

(23) by DitherSky · 35,731 downloads

Extension for auto-formatting and colorizing JavaScript code. Triggered by files with .js extension in their URL or by toolbar button.

YSlow

(20) by getyslow · 88,854 downloads

YSlow analyzes web pages and suggests ways to improve their performance based on a set of rules for high performance web pages. For more details, see http://getyslow.com/

URL Encoder/Decoder

(18) by Daniel Banon · 10,342 downloads

A simple URL encoder/decoder.

Simple REST Client

(18) by lennartc · 7,808 downloads

Construct custom HTTP requests to directly test your web services.

SeoQuake extension

(17) by seoquaketeam · 43,267 downloads

SeoQuake is a powerful and handy SEO extension. It shows tons of SEO parameters, also works in SERP.

Block Yourself from Analytics

(13) by Igor Jerosimic · 13,356 downloads

Block your Google Analytics activity for the websites you own, no more false stats.

Dust-Me Selectors for Opera

(12) by brothercake · 16,529 downloads

Finds unused CSS selectors, across a whole site or on individual pages

Resize Me

(12) by tagawa · 11,519 downloads

今見ているページの大きさを変更する。いろんなサイズの画面でウェブページを確認するには便利です。

Right Mouse Enabler

(12) by eevwa · 7,625 downloads

This makes right mouse context menu when it blocked.

Layers

(10) by andreasbovens · 7,405 downloads

This extension generates a topographic view of any web page and visualizes how its different elements are layered on top of each other.

XCodeViewer

(10) by extensible · 7,402 downloads

Powerful XML-viewer. Supported: syntax highlight, expand/collapse tags, XPath search.

MultiConvertor

(10) by DitherSky · 2,440 downloads

Extension for some common web-programming conversions with direction guessing option.

URL-Short

(10) by RusTorg · 717 downloads

"Сокращятель ссылок для Opera

SeoQuake Lite extension

(9) by seoquaketeam · 9,774 downloads

Displays Google PageRank and Alexa Rank of any webpage inside the browser window. SeoQuake Light is FAST and SIMPLE.

Visual Event

(9) by vgrischenko · 3,164 downloads

Visual Event extension is advanced tool to develop reach web applications. It provides information of events attached to DOM-elements on HTML-page.

blockNOTE

(9) by RusTorg · 1,980 downloads

"Блокнот" для Opera, который всегда под рукой

HTTP Header

(8) by Abhijeet Ashok Muneshwar · 10,627 downloads

View HTTP Response Headers of URL

PageRank

(8) by sergey-pypyrev · 8,796 downloads

Display Google PageRank of current page

geneLink | リンク生成器

(8) by cirretas · 762 downloads

現在開いているページのリンクをタイトルを添えて作成します。

HTML5 Button

(7) by Nickko · 10,340 downloads

Affiche l'icone HTML5 dans le bouton de l'extension si la page utilise le doctype HTML 5.

GitHub Notifier

(7) by sindresorhus · 3,803 downloads

Displays your GitHub notifications unread count

Form details

(7) by SKet82 · 2,073 downloads

Show or hide form details and hidden fields

Easy User CSS

(46) by BS-Harou · 16,596 downloads

Add CSS to any website

Xdebug

(6) by amakarov · 8,767 downloads

Allows to manage Xdebug debug session

pasgen

(6) by RusTorg · 5,782 downloads

Генератор паролей для Opera, который всегда под рукой

HTML5 Outliner

(5) by tagawa · 13,967 downloads

Outlines a web page's HTML5 elements

HTML Color Coder

(5) by Abhijeet Ashok Muneshwar · 10,054 downloads

This extension gives HTML color code value for selected color.

iMasters

(5) by redacaoimasters · 9,398 downloads

Notícias diárias sobre tecnologia.

JSCSS Highlighter

(5) by miketaylr · 4,620 downloads

Adds SHJS highlighting for .js and .css source files

Color picker

(5) by UnShame · 4,514 downloads

This extension lets you pick a color in HEX, RGB or HSB (HSL) format.

Seoptimer.com - SEO Audit

(5) by xradar · 2,854 downloads

Seoptimer.com - On Page SEO Audit. Quick and simple SEO analysis.

Lorem Ipsum Generator

(5) by sularome · 486 downloads

Generator of Lorem Ipsum text

Validator

(14) by DanielHendrycks · 20,730 downloads

Easily Validates pages with W3C's Validator

CopyButtonMaker

(4) by whochan · 974 downloads

ウェブページへのリンクコードを取得する Opera ボタンを作成します。

Console overlay

(4) by helmers · 637 downloads

See the console messages overlaying the current page.

Pimp My DevO

(13) by tagawa · 5,679 downloads

Automatically adds a seasonal atmosphere to Dev.Opera

LiveReload 2.0.1 (Beta)

(7) by gavro · 2,371 downloads

LiveReload refreshes a web page when files change. Please make sure you enable Websockets and LiveReload is installed and running. See here for more information on…

Reveal Cookies

(6) by tyuio211 · 2,732 downloads

Reveals all cookies used by the website. With this, you'll be able to quickly find out what information the website collects from you. Also allows you to change or clear…