Top 21 Firefox Addon every software engineers must know

Mozilla Firefox is a very popular browser, especially among web designers and developers. These days, with such a crowded field, staying at the top of the browser heap takes a lot of work. One of the factors that make Firefox so well-liked is the huge library of great extensions that enhance your browsing experience.

Among the massive list of add-ons, many are vital to web designers and developers. If used, it will make your workflow quicker and more productive. Let’s look at our top 21 essential Firefox extensions for web designers.

1. Web Developer

I absolutely recommend the ‘Web Developer‘ add-on. It gives you some great features which will make your development workflow faster. I enjoy various CSS, form, and image options. No matter if I want to check alt tags, missing images, or image dimensions, this add-on is my preferred choice.

History & Origin of Web Development

Where the Web was born. Tim Berners-Lee, a British scientist, invented the World Wide Web (WWW) in 1989, while working at CERN. The Web was originally conceived and developed to meet the demand for automated information-sharing between scientists in universities and institutes around the world.

CERN is not an isolated laboratory, but rather the focal point for an extensive community that includes more than 17 000 scientists from over 100 countries. Although they typically spend some time on the CERN site, the scientists usually work at universities and national laboratories in their home countries. Reliable communication tools are therefore essential.

The basic idea of the WWW was to merge the evolving technologies of computers, data networks and hypertext into a powerful and easy to use global information system.

How the Web began

Tim Berners-Lee wrote the first proposal for the World Wide Web in March 1989 and his second proposal in May 1990. Together with Belgian systems engineer Robert Cailliau, this was formalised as a management proposal in November 1990. This outlin

ed the principal concepts and it defined important terms behind the Web. The document described a “hypertext project” called “WorldWideWeb” in which a “web” of “hypertext documents” could be viewed by “browsers”.

By the end of 1990, Tim Berners-Lee had the first Web server and browser up and running at CERN, demonstrating his ideas. He developed the code for his Web server on a NeXT computer. To prevent it being accidentally switched off, the computer had a hand-written label in red ink: “This machine is a server. DO NOT POWER IT DOWN!!

2.User Agent Switcher

The User Agent Switcher allows you to switch the user agent of your browser. The add-on will add an option to the tool settings. This option lets you switch the user agent.


The User-Agent Switcher allows you to switch the user agent of your browser. The add-on will add an option to the tool settings. This option lets you switch the user agent.

The Basics

When your browser connects to a website, it includes a User-Agent field in its HTTP header. The contents of the user agent field vary from browser to browser. Each browser has its own, distinctive user agent. Essentially, a user agent is a way for a browser to say “Hi, I’m Mozilla Firefox on Windows” or “Hi, I’m Safari on an iPhone” to a web server.

The web server can use this information to serve different web pages to different web browsers and different operating systems. For example, a website could send mobile pages to mobile browsers, modern pages to modern browsers, and a “please upgrade your browser” message to Internet Explorer 6.


The Usersnap Firefox add-on lets you capture and annotate any website. It works great for collecting and managing user feedback on websites or applications or for tracking bugs in your browser.

All screenshots are directly saved in your Usersnap projects. It integrates with your workflow, and you can connect Usersnap with JIRA, Trello, Slack, and 20 other project management tools. A perfect fit for QA and development teams.

Compatible with your device

Capture your screen, collect user feedback, and track bugs reports on any website, prototype, or application.
Send feedback and report bugs on any website with screenshots and annotations directly in the browser.
Usersnap ( makes it easier for digital product teams to do user acceptance tests
(UAT) and communicate design and development feedback. Microsoft, Canva and other software companies streamline
QA and user feedback workflows with Usersnap. Usersnap can integrate with 50+ third-party solutions,
such as… Jira Slack Zapier WordPress Intercom Top 5 Features 1. In-Browser Screenshots:
you’ll get a screenshot of what your users experience. Quickly uncover browser-specific issues.
2. No-Code Installation: with the browser extension, there’s no need to install any additional code on your site/app.
3. Collaborate & Communicate: assign and track each item in Usersnap with your team. Add labels, attachments
and comments to work better together. 4. Console Log Errors: client-side javascript errors are captured with the screenshot.
Minimize your time troubleshooting. 5. Metadata Analyzed: Usersnap automatically includes the environment data to the tickets.
URL, browser info, screen size, time, and location are some examples. Plans Free for 15 days (no credit card needed!)


SeoQuake will help you in optimizing your web pages for search engines. It gives you a SeoBar that has loads of useful SEO-related options for you to take advantage of. This extension will assist you in identifying issues pertaining to search engine indexing in your web pages.

Semrush is a SaaS platform. It is often used for keyword research and online ranking data, … “SeoQuake Presents New SEO Product for Analyzing Web Sites’ Search …

What is SEOquake?
SEOquake is a free plugin for your browser that provides you with organic search data at the click of a button. … Along with organic research data, SEOquake provides other useful tools including an SEO Audit, Keyword Density report, Internal/External Link analysis and even social metrics.
How do you use SEOquake?


FireShot is a Firefox add-on that creates screenshots of your web page. What is unique about this plugin is that it gives you a set of editing and annotation tools for working with your screenshots. This can be a handy extension to have for presenting your work in your portfolio.

How do you use FireShot extensions?

How to use the Fireshot addon for Firefox

  1. Step 1: Open up your Firefox Browser. …
  2. Step 2: Install Addon. …
  3. Step 3: Restart Firefox. …
  4. Step 4: Open Firefox and view your options. …
  5. Step 5: Using the “Capture Visible area and …” section. …
  6. Step 6: Using the “Capture Selected area and ..” section.

Is FireShot secure?

The software can be used to transform live pages into relevant information by saving the particulars in the form of JPEG, PDF, PNG, GIF or BMP. The saved data can be uploaded on Microsoft OneNote or other external programs. FireShot provides optimum security to user data by storing the screenshots within their PC.

Is there a free version of FireShot?

FireShot is a free software only available for Windows.


Ghostery is a great add-on to display installed trackers and pixels of any website. It helps you to find and analyze the used marketing- and tech stack of any website. And you can block them if you don’t want your session to be recorded.


Firebug is considered to be the ultimate developer’s tool for F

irefox. You are given a ton of web development tools to use from within your browser. You can explore, edit, debug, and monitor CSS, HTML, and JavaScript in real-time on any web page.


The Greasemonkey Firefox add-on enables you to modify how a web page looks and works by using small snippets of JavaScript. There are hundreds of scripts that you can download to enhance this add-on.


ColorZilla is an advanced color picker and eyedropper. It allows you to get the color of any pixel in the browser window. The extension also has a built-in averaging square. This helps you get a matching color to for a photo. The add-on is pretty simple and easy to use.


FireFTP is a streamlined Firefox extension for uploading files to a server. It offers several advantages to standalone FTP applications, such as its operating system-independent requirements. This browser add-on has all the features you would expect from standalone apps.

11.HTTPS Everywhere

This Firefox add-on encrypts all your communication with many major websites. As many sites support HTTPS, they still might use HTTP. Or they fill encrypted pages with links that go back to unencrypted sites. The HTTPS Everywhere add-on fixes these problems by rewriting all requests to HTTPS.

12.Palette Grabber

This add-on will build color themes that are exportable to popular graphic-editing software such as Photoshop, Paint Shop Pro, GIMP, Fireworks, and Paint.NET of the web page you’re currently viewing.

13.Total Validator

This extension is an all-in-one validation tool that will check HTML, links, take screenshots, and do a lot more. It also performs accessibility validation (WCAG, US-508), broken link checking, spell checking (in five different languages), and take screen captures via different web browsers and operating systems to see how your web pages look.


The BuiltWith add-on analyses websites and their technologies, servers, and hosts. It works great for analyzing competitor websites and you can get insights on any web page. And it even displays tracking IDs, like the Google Analytics ID.

15.Web Developer Checklist

The Web Developer Checklist is a simple add-on that gives you an overview of the usability of your site.


Hands down, Platypus is one of the best Firefox extensions for modifying a web page. It works with Greasemonkey as a sort of WYSIWYG and it will remember your edits when you visit the web page again. You can use it to experiment with different variations of a web design.

17.Dummy Lipsum

An add-on with a very simple purpose, Dummy Lipsum generates Lorem Ipsum dummy text for you to use in your designs.

18.Cookie Manager

This Cookie Manager lets you check and manage the cookies. You are able to view, add, change or even delete cookies in any of the domains. You can even export and import cookies. This is helpful to reproduce certain issues by recreating certain browser sessions.

19.Page Performance Test

It analyses web pages’ performance based on various parameters. The Page Performance Test measures network, browser, and server performance. You can use Page Performance Test directly on your console:

  1. Open up your console; you will now find a new tab “page performance”
  2. Start the performance test.


CSSViewer allows you to inspect CSS properties on a web page that you’re viewing. It’s a great way to study styles that you’ve seen on websites to learn CSS development techniques.


Aardvark, aimed at front-end web developers, lets you select web page elements and gives you several options for them, such as removing them from the web page (great for screenshots) or modifying their colors (helpful when printing web pages).



Rajesh Kumar
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