10 Firefox Add-ons for Web Designers
Firefox has emerged victorious from the Great Browser War – at least as far as web developers are concerned. While it may not be the most-used browser for the everyday web surfer, Firefox is clearly the first choice of developers for a few very simple reasons. Its support for web standards is legendary, but the real super powers come from Firefox’s extensibility. With a plethora of add-ons and extensions, created for developers by developers, Firefox becomes much more than just a browser and turns into an essential part of your toolbox. Rather than digging through your source code with squinted eyes, use Firefox add-ons to pinpoint Javascript errors and debug them like a pro. Use add-ons to measure areas of your page, select colors directly from the site or view the specific CSS assigned to a pesky <div> element. You can even get a leg up on assuring your sites are accessible and use valid markup – all thanks to Firefox’s add-ons.
Here are 10 free add-ons covering everything from DOM inspection to screenshots, making designing and developing with Firefox a breeze.
1. Firebug + Firecookie + Codeburner
The first on our list of 10 is actually 3 separate add-ons but they are all meant to work together, and when combined they form one of the most powerful development tools available.
First and foremost, if you’re doing any sort of Javascript development Firebug is essential. Otherwise you’re really just stumbling around in the dark when it comes to debugging. Firebug not only gives you a robust error console, but also lets you add breakpoints in your code. Firebug’s HTML and CSS inspector gives you the freedom to either browse your source code in a collapsible tree, or click an element within the page to see its markup. Firebug also lets you edit your “live” HTML and CSS and instantly displays the results for you to review – no reloading, no saving.
Install the Firecookie add-on and Firebug gets a new super-power: complete cookie viewing and management. You can view the full content of each cookie, and even edit and delete them all from Firebug’s window.
Codeburner then rounds out the Firebug setup by adding a compete W3C reference lookup with search-as-you-type on HTML elements & attributes as well as CSS properties. Ever wonder which browsers support the text-transform CSS atrtribute? Codeburner will tell you that it’s buggy in IE7, but has full support in Firefox 3, Safari 3 and Opera 9.
Get Firebug, Firecookie, Codeburner
2. Web Developer Toolbar
If writing Javascript without Firebug is like fumbling in the dark, building a site without the Web Developer Toolbar is like blindfolding yourself, tieing your hands and and trying to run through the woods without hitting a tree. Disable your cache, images and cookies, switch style sheets by media type, auto-fill forms with temp data, outline certain element types, resize the browser window to common sizes and validate your markup – all from within one toolbar. The Web Developer Toolbar does a whole lot more and is always the first add-on I install in Firefox. Give it a try and you’ll wonder how you ever got along without it.
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3. Measure It
Ever need to know just how much space you have for a photo, or how wide a dynamically sized column is? This handy little guy lets you measure, in pixels, any area on the page. Super simple and super helpful.
Get Measure It
4. Colorzilla
Another very simple but very useful add-on that displays the RGB and HTML color codes directly beneath your cursor. With a click, Colorzilla will copy the HTML color code to your clipboard for use in your favorite editor.
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Get Colorzilla
5. CSS Viewer
CSS Viewer takes one of the features in the Web Developer Toolbar and makes it a little easier. Just point your cursor at any element on the page and CSS Viewer will show you all of its CSS attributes, from size and position to fonts and colors, all in an easy to read overlay.
Get CSS Viewer
6. Screengrab
A simple screenshot tool, Screengrab will save the visible area or the complete page as a file on your desktop. You can choose to save as a png or jpg, and even auto-add a datestamp to the file name.
Get Screengrab
7. Gridfox
If you use grid layouts or want to learn how, Gridfox is for you. It displays a simple overlay on your page to help you align elements to both vertical and horizontal grid lines. You can easily set the column and row sizes and spacing, choose from left-aligned, right-aligned or centered layouts and set the opacity of the overlay.
Get Gridfox
8. Firefox Accessibility Extension
See how your pages will be displayed when viewed with assistive devices – high contrast, images disabled, etc. This add-on will go a long way in helping you design accessible sites and includes links to FAE, WAVE and other accessibility evaluators.
Get Firefox Accessibility Extension
9. User Agent Switcher
If you swap style sheets or display alternate content based on which browser the user is viewing your site with, this add-on will tell Firefox to pretend it is another browser. Choose from Opera, Internet Explorer, or add your own custom user-agents to the list.
10. PageDiff
Those of you familiar with the linux/unix “diff” command will instantly understand what this add-on does. Compare the source code of any two pages and see where they differ. This is very useful when comparing staging and production environments, or comparing a backup to a current deployment before restoring any code.
Get PageDiff


Very useful post. I knew about some of these but the measure it add on is a revelation. Many thanks.
Firefox rock and is more coOler with its awesome add-ons
Cool, nice post. But the extension web developer can do many things (grid, css, color,…)
@ ian: While it’s true that the Web Developer Toolbar does a lot, it doesn’t do everything. It will display CSS info, but (as I noted) I think CSS Viewer handles that task a little better. Likewise, the toolbar will let you measure areas (Miscellaneous -> Display Ruler), but I think Measure It does a much better job and is accessible with just one click.
With any single kitchen-sink add-on you’re likely to have some overlap into what other add-ons do, and perhaps do better.
Truly a wonderful list! Thank you!
A fantastic compilation of plugins. I’ve downloaded them all (whereas I only had firebug previously) and find each one to be quite useful.
Kudos!
A couple of good points, thanks.
Very nice list of add-ons, but more importantly, your explanations are clear and concise. Anyone can download anything, but not everyone has dedication to fiddle with all add-ons. Your review helps a lot, thank you for that.
PS: for some reason, your font renders strangely, and is quite difficult to read (in Google Chrome and Firefox).
@ hiddenson: I’ve just tested this page in both Firefox and Chrome in XP, and Firefox in OSX. The page is rendering perfectly. Can you email me a screenshot of what you’re seeing along with the OS version you’re using?
Don’t forget aardvark! It is the #1 tool I use when coding and debugging. Without it I am just lost! Also “Screengrab” is useful if you need to take whole page screenshots of designs!
@ Lindsey: The web developer toolbar has a feature called Display Element Information (under the Information menu) that does a lot of what Aardvark does. You can also start this feature with a hotkey, and it displays all relevant CSS and other info for any element you put your mouse over. I’m interested to see how Aardvark turns elements off though, so I’ll definitely check it out. Thanks!
very useful list – dont forget SearchStatus
I really loved the css viewer!
abduction is another alternative add-on to screengrab.
Great Aritcle About 12 Firefox Add-ons for Web Designers |
[...] found this article today on a Linkedin group I joined called Communication Arts (posted by Jeff Couturier) about 10 [...]
Great list. I did not know about measure it and it really comes handy.
Nice work putting together this list. I use some, others are good to know.
Nice list. I went and got all of them.
I would like to add that Greasemonkey is another great extension for any firefox user.
Nice collection. Especially like the User Agent switcher. Been using view in IE along with others.
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Thanks to this list I learnt about Codeburner, Gridfox and FAE. Really useful, thanks!
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links for 2009-05-11 | 雷都散策記
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10 things to learn on May 11th
[...] 10 Firefox Add-ons for Web Designers | 10 Volt Media Blog irefox has emerged victorious from the Great Browser War – at least as far as web developers are concerned. While it may not be the most-used browser for the everyday web surfer, Firefox is clearly the first choice of developers for a few very simple reasons. Its support for web standards is legendary, but the real super powers come from Firefox’s extensibility. With a plethora of add-ons and extensions, created for developers by developers, Firefox becomes much more than just a browser and turns into an essential part of your toolbox. Rather than digging through your source code with squinted eyes, use Firefox add-ons to pinpoint Javascript errors and debug them like a pro. Use add-ons to measure areas of your page, select colors directly from the site or view the specific CSS assigned to a pesky <div> element. You can even get a leg up on assuring your sites are accessible and use valid markup – all thanks to Firefox’s add-ons. [...]
I am so glad I stumbled on this blog. Thank you so much, I am going to download these as soon as I get home.
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[...] 10 Firefox Add-ons for Web Designers | 10 Volt Media Blog (tags: webdesign firefox extension) [...]
It is nice to have all of them at one page. This is very useful list for the web developers.
Thanks a lot.
Very good add-ons, looks like I’m going to have to try some of these. Thanks for making the compilation!
Bookmarks for May 8th through May 11th :: Jamie Riddell
[...] 10 Firefox Add-ons for Web Designers | 10 Volt Media Blog – With a plethora of add-ons and extensions, created for developers by developers, Firefox becomes much more than just a browser and turns into an essential part of your toolbox. [...]
Thought you might like to know about this (if you don’t already): http://tutorialblog.org/10-firefox-add-ons-for-web-designers-you-might-not-know-of/
Great compilation…thanks for the post!
Uber useful!! Thanks a lot!
Daily Digest for May 14th | Loudmouthman
[...] 10 Firefox Add-ons for Web Designers | 10 Volt Media Blog — 9:21am via [...]
Not a Firefox addon, but an alternative for Screengrab would be SnagIt screen capture program. It has good editing capabilities, you can add notes fast and it saves all your captures automatically. You can sign tags for the pictures and use SnagIt as a fast and effective screenshot notebook. You can capture long windows (snagit has automatic scrolling) and even record short movies if you want to record how some application or form works. SnagIt outperforms the firefox addon anytime.
I think that “dummy lipsum” add-on has to be the 11th add-on for web-designers! ^_^
neat
thanks for these links
measure it is something i have been looking for
thank you
@ LoreM9 – Good call. My own habit is to use MacLorem (OSX desktop app) for generating lorem ipsum, but the Firefox add-on is great too. For anyone else that’s interested, here is the download link for Dummy Lipsum.
Amazing.
These are all good services. I’ve been using them for a while, and couldn’t do without them.
Nice list, thank you.
makes slow fox even slower and just harder to say goodbye. lol
but im still sticking to my opera and dragonfly+debug menu not as powerful as this but it’s a neat tool
Webdevelopper toolbar makes most of these already. No need to install tons of plugins
Great list.
I’d also add HTML validator extension, (http://users.skynet.be/mgueury/mozilla/) as it gives you a very easy way to check the validity of your pages without going to w3c. It also integrates tidy, so it can automatically (sort of) fix problems. There’s no better way to ensure you’re writing valid code.
Great list, thanls for sharing !
I’m not a professional web developer but I do tent to play with my themes and the tools you have mentioned comes in pretty handy. CSS option given in the web developer toolbar comes in very handy for someone who knows a bit of coding but don’t have an advance knowledge of CSS
So cool. Didn’t know some of these options existed. Firefox is such a great tool. Thanks for the list. Good karma to you.
Thanks a lot, many time i have searched for such addons at addons.mozilla but never get this much helpfull results, it helped alot agent switcher is the best, now not to worry, opening site in multiple browser at the same time.
Great list! I have about half of these, but I’ve been looking for that ruler (Measure It). Gotta love FF.
I would add FireFTP also. Very nifty free addon that I use all the time.
nice
FireCookie is neat. Never heard of it before. Great post. Thanks. Very useful info here!
Thumbs up on Stumble
A lot of these were new to me. MeasureIt happens to be my favorite. Thanks again!
I really like web developer but tamper data is useful too, for debugging http-requests and such.
Very cool thanks!
Just stumble to this page and of course I have to thumb it up
. Great add-ons every designers should use.
Hey Jeff,
Just thought I would mention, in case anyone takes a look here… Codeburner is not currently compatible with Firefox 3.5 (which was apparently just released not long ago)
Actually, Firefox 3.5 has not been released yet – only the betas and release candidate. So it’s quite safe to assume that Codeburner will be ready once Firefox 3.5 actual is released.
My Bad. For some reason Firefox at home updated and removed all the RC tags around the 22nd. Reports from CNet and looking at mozilla.com show Firefox 3.5 as having been released now, but Codeburner is not yet updated for 3.5. I’m sure it will be in the coming days however.
Its really useful article. I was aware of only 2 of them. Thanks for writing this article
Thanks very useful and informative! Did anybode know a video screen capture plug in for firefox?
Thanks for Sharing!
Good Stuff everyone should give this a tweet…
Vital piece of information many of them are new to me thanks
I have been using many of these for a while since first coming here; the Web Developer Toolbar is particularly valuable… just dropped by to get the URL for this page to recommend to a friend, and thought I would post a thanks for this great collection.
This is a great collection of different ad ons for the toolbar. As a webdesigner i use it every day in our company Dreamland for the professional use. some adons make it very easy to check the correct settings of graphics in the css. so i strongly recoment firebug to check the code.
10 Firefox Add-ons for Web Designers | Larry Ullman's Blog
[...] been meaning to mention this useful post—10 Firefox Add-ons for Web Designers—for some time now but never seem to get around to it. Anyway, it’s a short, efficient read, [...]