10 Essential Firefox Add-ons for Web Developers

When Firefox was released in 2004, it was the primary browser for most people, with a few exceptions who used Opera or Internet Explorer. It is known to be a simple yet powerful web browser that offers only what you need to browse the Internet as fast and possible, but it is also extendable in many ways.

Since then, Google Chrome came out and it came to dominate the market, making Firefox only the second best web browser. Chrome brought a lot of good to our Internet experience and Firefox still aims to be as open as possible, which is why it is a prime choice for many, especially developers. Firefox simply works and can be customized, extended and basically set up in a way that fits your needs perfectly.

Today, we spend most of our time in web browsers. As the Internet grows and technologies develop, more and more web based applications come out, which we can simply access from our browsers. This really is a logical step forward, because almost anyone can have access to an application that runs in your browser.

One of the most demanding tasks one can do online is coding and development. It requires a completely different perspective then just browsing through content, so it’s good to have the right tools for it. These tasks require a lot of insight and precision.

Making sure that we use accurate measurements is also very important. The list goes on and web development gets more advanced every day, requiring us to adopt with new tools and technologies.

In this article, we’ll give a list of the best add-ons that make web development a much easier process. It continues our Firefox add-ons series, where we cover the best add-ons for specific tasks and people. Let’s see what kind of developer tools we have!

Web Developer

web developer firefox addonThe Web Developer add-on adds a number of web development tools and menus to the Firefox browser, making your workflow much faster. With these, you’ll have a much easier time analyzing, validating and optimizing web pages. You can use it to validate your website according to accessibility guidelines and web standards.

One of the best features that the Web Developer toolbar has to offer is the ability to a page’s CSS or HTML elements allowing you to test different designs on the go. The changes you make will appear on the webpage instantly. Browser features such as JavaScript, caching, CSS and images can be temporarily disabled.

Different tasks are grouped into categories such as „Images” or „CSS”. You also have the option to display a ruler that follows images.

This extension is a must-have for any webmaster or web developer out there.

Get it here!


firebug firefox addonThis is one of the most popular Firefox add-ons that many consider the ultimate extension and for a very good reason. It is powerful and puts many web development tools at your fingertips. You can view and edit any HTML, CSS or JavaScript code, being able to instantly change the result within your web browser. Meaning, you don’t have to save a file to see the changes on your website.

It also helps you find errors pretty fast, making it a great debugging tool that will help you zero out any Javascript errors in no time. Precision is of key importance when you’re working with CSS so you can make great use of the ruler and guide features. You can also explore DOM objects, view cookies and monitor your web activity.

Firebug’s functionality can be amplified by the large number of extensions available. With applying further extensions, you’ll have yourself a fully featured development kit in Firefox. No wonder many people see this as the ultimate development add-on.

Get it here!


flagfox firefox addonThe Flagfox add-on makes it really easy to learn about a website. It provides a lot of useful information like the country where a website is hosted. You can get it by clicking the flag icon beside the URL of any website. You’ll get a dropdown menu, where you can do things like virus scanning, translation and many more. Its offers a lot of help with the security aspects of a web development project.

Get it here!


This add-on lets you inject JavaScript into any webpage, letting you change the content in a webpage. Run a JavaScript on a website and alter it according to your liking, making the change permanent.

Greasemonkey lets you control various aspects of a website’s appearance with user scripts. If you don’t know how to or don’t want to create your own user scripts, you can choose from the thousands that are available at UserScripts.org.

Get it here!

HTML Validator

html validator firefox addonIt’s important to make sure that a website is displayed equally well in every web browser and avoid having to fix it later. For this purpose, there are a couple of techniques that can be used to make sure that your website fits into requirements.

One of these methods is validating your HTML code with the HTML Validator add-on. It helps you verify your code’s accuracy by following W3C’s guidelines.

Get it here!


colorzilla firefox addonColorZilla gives you a lot of control over the colors of any website. You can manipulate it all to your liking or get the codes of colors you come across. Just select any text within a webpage and ColorZilla will give you its color code. It’s a slick add-on that will prove beneficial in many web development scenarios.

Get it here!


imacros firefox addonAutomating repetitive tasks was never easier. If you’re working a lot in your web browser, this add-on can take a lot off your shoulders. You don’t have to type the same stuff over and over again. All you have to do is create a macro and it’s all set. It is exceptionally good for scraping data or data entry.

iMacros lets you record a certain macro and it will take care of it on its own from there. This is great for filling in forms, creating webmail notifiers, remembering passwords or downloading information from websites. Make your work easier for yourself and give iMacros a try.

Get it here!

SEO for Firefox

seo toolbar firefox addonOne of the best SEO tools for Firefox, although there are many you can choose from. With this one, you can search for your targeted keywords on Yahoo! or Google and then click the SEO icon to start using the add-on.

It will give you a lot of useful, SEO-related information like a website’s rank in Google, your entry’s position in search results, a website’s age, the number of inbound links on a page and so on.

What makes this add-on different from others is that it displays links to this information, instead of displaying the information itself. This might be a turn off, but it’s actually a good thing, because your computer might get blocked for requesting too much information at once. You can use this SEO add-on safely at all times.

You’ll have to register for an SEO Book account to get your hands on this add-on, but it will be well worth the effort.

Get it here!

Save Complete

Save Complete lets you truly admire someone else’s work by saving an entire webpage, including all of its associated files. You can do this in other ways as you might already know it. Using Firefox’s „Save Page As” function or add-ons like Web Developer and Firebug can do this as well, but they’re much more limited.

Save Complete can do a great job in saving an entire webpage along with all of its Images, CSS or JavaScript files into a folder you specify. It is one of the best options you have when you want to download sites for experimenting, learning or doing anything that your hearth desires.

Get it here!


restclient firefox addonIt can be a long and bothersome task to debug web services, but RESTClient offers a simple solution to do it with more ease.

You can easily see the responses for HTTP requests and inspect the response headers. RESTClient will tell you if your request succeeded or not and you can examine the response. It’s a really quick and simple, yet powerful tool that can save you a lot of time and streamline the debugging phase in your project.

Get it here!


This concludes our article about some of the most powerful web development add-ons for Firefox. All of them will save you a lot of time and effort in debugging, inspecting and precisely developing your webpage. We’ll be coming back with another article that covers more Firefox add-ons and tools that can help in making web development a more seamless process.

I hope that you enjoyed reading through this article and more importantly, that you have found all the information you were looking for. Stay safe and stay tuned for more!

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