Hi All,

What firefox plugins could you not live without, as relates to webdev?

My list would be:

I am always on the lookout for new ones though, so I wonder if anyone knows of any great ones that I may have missed?

+17  A: 

Firebug is the main one I use.

Andrew Rollings
a link would be handy for those who don't already have it
Here you go! ;)
Andrew Rollings
(I know, I know... not funny ;) )
Andrew Rollings
+9  A: 

Web Developer is quite useful (firebug Andrew mentions is no doubt #1)

Cristian Libardo
+3  A: 

TestGen4Web - Just like your VCR - for Firefox. It records what you do, stores it, and plays it back on demand.

  • Web Developer
  • Firebug
  • Delicious

Might also add Page Validator

+2  A: 

Firebug, Web Developer toolbar and YSlow for Firebug are some of my picks.

+5  A: 

Live HTTP headers, in addition to some already mentioned.

+5  A: 

IETab is a nice to have (IE in a Firefox Tab)

This is excellent for quickly checking a layout in IE. It uses the installed version of IE for its rendering.
+3  A: 

the HTML Validator plugin is priceless, especially when you're working on stuff written by someone else who may not be so careful with standards compliance...

+3  A: 

NoScript. Not just for blocking spam - it's a lot quicker than flipping the script setting on and off manually, and lets you simulate third-party servers going down.

You can also get a lot of useful info just from Firefox's built in error console (in the Tools menu) - among other things it'll point out broken CSS code.

Ant P.
You can disable all javascript using Web Developer toolbar.
+1  A: 

ff-activex - allows to use active-x plug-ins in Firefox

Eran Galperin
+4  A: 

YSlow - analyzes web pages and tells you why they're slow.

MeasureIt - Draw out a ruler to get the pixel width and height of any elements on a webpage. Even better is the Xray bookmarklet.

Hackbar Simple security audit / Penetration test tool.

FirePHP is a Firebug extension for AJAX Development

ColorZilla 2.0 is an advanced eyedropper, colorpicker, page zoomer and some other things.

If you already use the Web Developer add-on, it does have a ruler buried in it's options somewhere. I use to have MeasureIt installed before I discovered this.

Firebug is the greatest.

Also, not a dev tool but I have found it very useful and easy to use, Foxmarks bookmark manager.


Two other ones that I use are ...

  1. Search Status (SEO related)
  2. Ad Block Plus (Blocks Ads)

Many of my favourites have been mentioned. To these I'd add:

  • Adblock Plus: removes ads
  • Add-Art: replaces ads with art
  • Auto Copy: copies to clipboard on select
  • Tree-Style Tab: shows tabs like a tree

Some of my favorites among others which already mentioned ,

  • TabKit - Shows tabs in separate panel , closes the tabs in groups , grouping of tabs.

  • Morning Coffee - restore the tabs those are saved to view them later.

  1. Undo closed tabs. This is what I miss from IE8.
  2. FEBE, for backing up the settings of Mozilla.

In addition to already mentioned addins:

  • ViewState - Displays the current ASP.NET page viewstate size in the status bar.
  • ColorZilla - Advanced Eyedropper, Color Picker, Palette Viewer and other colorful goodies for your Firefox
Martin Vobr

Besides the ones already mentioned (especially the marvellous Firebug), these are the development related ones I've found very useful:

  • JSONovich does a good job at pretty-printing and colorizing JSON.
  • User Agent Switcher is very handy for developing mobile web sites (or just for the sake of curiosity) -- "I'm an iPhone, reveal me your contents!"
  • Sometimes Firefox leaves stuff in the browser cache even on reloads. The Clear Cache Button helps with this.
  • Header Spy is similar to Live HTTP headers, but displays header information (and access to lots of more options) in the statusbar.

Xmarks is a good extension for backing up bookmarks, and allowing them to be synchronised between different machines. They have bloated it with other additions recently, but these can be turned off through the options.


I (ab)use Stylish to experiment with/prototype css changes. Yes you can do it in Firebug but it's not easy to keep track of all the edits you've made and it's not easy to copy & paste those edits back into your css file. Also, if you hit F5 you lose all changes made in Firebug.

Stylish survives page refresh and since it's just text you can simply select all to copy & paste your changes. Of course, it doesn't provide a css inspector or a DOM tree view but that's what Firebug is for.


Another one I use a fair amount is the Amazon S3 Firefox Organizer (S3Fox)

Scott Evernden

In addition to those already mentioned, Selenium IDE.

+5  A: 

No mention of Greasemonkey or Mason?

Avindra Goolcharan
Greasemonkey is a must have in my book.
Talvi Watia

I've found Venkman to be useful recently, in addition to firebug and others already mentioned.

Venkman aims to provide a powerful JavaScript debugging environment for Gecko-based browsers...


I find it interesting that so many people name a significant number of addons that Web Developer toolbar does for you. While they are all great plugins and might have a couple extra options, not sure if its worth it to have those plugins (for instance, MeasureIt)

Here is my list:
- Web Developer Toolbar (if you're a web developer [period])
- FireBug (essential for javascript/AJAX debugging)
- Google Page Speed (similar to YSLOW but it's from Google, very useful)
- ColorZilla (great color picker)
- HTML Validator (saves a bunch of time loading's page)
- Tab Mix Plus (anything and everything to do with tabbed browsing)
- Screengrab (if you use screenshots at all, use this) - Google Toolbar (SEO)


My list of addons which I use for development is:

I think those are essential for proper web development.

Ondrej Slinták