The Best Firefox Extensions for Web Developers

Firefox is currently one of the developers’ favorite browsers, not only for rendering more than just the correct pages, but also for the multitude of extensions that have emerged for everyday web design support. Some are of course already known and used by most readers of Microsoft Top.


If you had to have one, it would be Firebug. Manipulating the HTML DOM, CSS style sheets, and live JavaScript is a must.

Not to mention the tab of network queries, the very convenient inspection of the elements by the cursor of the mouse, the display on-printing margins, and the execution of JavaScript code on the fly and its console.

Firebug can be Supplemented by 3 “Sub-Extensions”:

YSlow: Developed by Yahoo, to improve the speed of loading pages based on best practices (cache, page compression, HTTP requests …)

Fire Scope: Integrates HTML and CSS documentation with support tables by browsers.

SenSEO: At YSlow, but to analyze the semantic structure of pages and improve their referencing according to predefined criteria.

Web Developer Toolbar

Venerable extension acclaimed since the beginnings of Firefox, Web Developer Toolbar includes in a toolbar most of the operations facilitating the integration and diagnosis of a document: Activation / deactivation / editing of CSS, JavaScript, consultation and modification of cookies, and display many information about forms, images and source; resizing the browser window, or W3C direct validation menu, it is difficult to summarize all that allows this best-of-all-in-one, each menu is to explore.


Html Validator performs an automatic validation of each page viewed, displaying the results in the status bar of the browser by detailing them during the consultation of the source code. RSS Validator has a similar purpose for RSS feeds.

IEView / IE Tab

IE View launches a view of the current page in a new window of Internet Explorer while IIS Tab allows its display inside a Firefox tab.


Colorzilla is essential to target an element with a pipette and determine its color. The “copy color to clipboard” option is also very useful for hexadecimal and RGB formats. Not to mention the integrated color palette.


Fireshot allows you to take screenshots of sites, copy them to the clipboard, save them as an image or edit them (a bit). We can take into account the visible part only (the one in the display area of the browser) or the entire page (hidden according to the resolution of the screen). Also exists for Internet Explorer.

Note the presence of two other extensions of this type: Pearl Crescent Page Saver Basic which is lighter (no editing) but does not include the visual content generated by Flash (areas appearing empty), and Abduction that captures the entire page or a specific area that is selected with the mouse.

Dust-me Selectors

Dust-Me Selectors finds unused CSS selectors in your style sheets, based on the current page viewed or a set of pages during a visit.


Measure it helps to accurately measure the dimensions of the elements of a page, using the mouse.


SmushIt is the counterpart of the eponymous site to re-compress as much as possible the pages contained in a page, maximum efficiency.

FirePHP / FirePython

FirePHP and FirePython are complementary Firebug tools for bug tracking in PHP and Python, sending selected error messages to the Firebug console.

Live HTTP Headers

Live HTTP Headers is for developers a quick way to view HTTP requests issued by the browser for any page lookup as well as complete server responses.


X-Ray unambiguously reveals in the page the (X) HTML tags used for each block. Useful for diagnosing a site, it’s DOM and its semantic structure.

We no longer present Grease monkey which allows via an immense amount of scripts to modify the content or the behavior of the pages visited, according to their address. The scope is far too broad to be summarized in a few lines as the possibilities are endless, and you? Which extensions do you think are absolutely essential? Which would make you happy if they saw the day?

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