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8+ Best Firefox Add-ons for Developers in 2023!

From coding to clearing the cookies, Firefox Add-ons for Developers help developers to manage their tasks. Some of the best Firefox Add-ons for Developers are Octotree, HTML Validator, HTTPS Everywhere, Cookie Manager, Colorzilla, User-Agent Switcher, Ghostery, Page Performance Test, etc., which are available for free on the store.

Firefox is said to be one of the most used browsers globally. It is fast, efficient, and provides excellent privacy and security to users. Many users prefer using Firefox over Google Chrome. I also use Firefox more frequently than Chrome due to its speed and other features that make my work easier.

Firefox offers various features that can be helpful to anyone in any group. Be it a student, teacher, or developer, Firefox has something in store for everyone. However, if it fails to offer all the features in its browser, it enables users to use these features as add-ons.

As a developer, I find managing all my tasks at once challenging. The list is endless, from coding to clearing the cookies, so the browser doesn’t hang. Although all these features can not be managed at once on Firefox, the add-ons do a pretty decent job of helping me.

I had quite a hard time sorting out the best add-ons for me. But after a lot of research, I have created a list of the best add-ons that I think will be helpful to you as a developer. Let’s have a look!

HTML Validator

If you are looking for an add-on that helps identify errors in your HTML codes, then you are at the right place. HTML Validator does precisely that for you.

It will point out all the errors for you, which will help you do all your work twice as fast.

HTML Validator Firefox Developer Add-on

Some of HTML Validator’s notable features are:

  • It helps validate the HTML that you currently have or have been sent by someone.
  • You can see the errors clearly and rectify them henceforth.
  • The rectification takes place entirely on your server.
  • No third-party apps or websites have access to your data.
  • It can be translated into 17 different languages.

However, it may show issues with rectification sometimes, as it may fail to identify all the errors at once, and you may have to wait for the same.

Download HTML Validator


Are you someone who is constantly struggling with your codes and their sources? With the Octotree Firefox add-on, you do not have to go to GitHub repeatedly to check for your codes.

All the things can be done with a single click now. Octotree can be helpful to coders around the world.

Octotree Firefox add-on

Several of Octotree’s top aspects are:

  • It enhances the way you code.
  • You have access to choosing the code’s font as well as theme.
  • You can manage multiple tabs for your codes.
  • You can also choose the font for your file icons.
  • You can manage multiple GitHub accounts with this.

Although it has excellent features, only a part can be accessed in the free version. Most of its features are available only in the pro or paid version.

Download Octotree

Page Performance Test

If you are constantly worried about your web pages loading slowly or getting easily irritated by the same, then Page Performance Test will help you calm down. It gives you all the necessary data about website speed and loading time.

You can also save all these data for future reference or comparisons.

Page Performance Test Firefox Browser Add-on

To name a few of the Page Performance Test Add-on’s unique features:

  • It measures the performance and speed of a website by using Web APIs.
  • You can save these for later.
  • It’s straightforward to install and get it running.
  • It gives you an accurate picture of page load time and statistics.

However, it may take quite some time to give you the results, which may be irritating when you are in a hurry.

Get Page Performance Test


If you use screenshots daily and annotate them for various purposes, Usersnap will be your favorite add-on from now on. It helps you take screenshots and annotate them as per your will.

This add-on has helped me a lot when I attach a screenshot to an article.

Usersnap Screenshot Firefox Add-on

Some of Usersnap’s essential features are:

  • You can take screenshots from websites and mark them.
  • You can also add comments or feedback in screenshots.
  • It also enables you to file a bug report.
  • It comes with a 14-day trial period.

Though it’s nearly perfect with all its features, it is a paid service, and not everyone can afford it. The trial period also ends after a mere 14 days.

Download Usersnap

User-Agent Switcher

This is a highly efficient Firefox add-on since it lets you switch your browser’s user agent. All this can be achieved very simply.

You can use this add-on for your work even if you’re not a technical geek.

User Agent Switcher and Manager Firefox Add-on

Some of User-Agent Switcher’s remarkable features are:

  • You can have access to websites that you didn’t earlier.
  • Not all websites will ask for a subscription when you change the user agent.
  • You can also use a new language for the user-agent switcher.
  • You can also report a bug or issue that needs fixing.

However, it may not work on specific sites and pose problems. This may cause inconvenience for you later.

Get User-Agent Switcher


Ghostery is one of those add-ons that will prevent you from distractions and protect your privacy. It helps in letting you know about trackers.

You can disable the trackers that steal your data or sneak into your private information.

Ghostery Privacy Blocker Firefox Add-on

Ghostery is packed with so many excellent features. Some of them are:

  • It blocks all unnecessary data or ads.
  • You can view or block trackers as well.
  • It loads a page faster and optimizes page performance.
  • All your data is labeled anonymous for more privacy.

Although it has many features, it still has its share of demerits. This add-on may have access to much of your information, which can lead to data loss or threaten your privacy.

Download Ghostery


If you have been looking for a color picker for a long time, your search ends here. With Colorzilla, you can choose any color for the browser window.

It also enables you to have a matching color for any picture you want.

ColorZillla Color picker as Firefox add-on

Several of Colorzilla’s fantastic features are:

  • It has an eyedropper that lets you have any color for a window.
  • It has an advanced color picker that’s similar to that of Photoshop.
  • You can view your recently picked colors in color history.
  • You also have a Web page Color Analyzer.

However, it may not apply the color immediately when you pick them; it takes some time. It can be a bit annoying.

Download Colorzilla

Cookie Manager

If you want to delete or edit your cookies, the Cookie Manager Firefox add-on will do it. It helps you view, add, or make changes to the cookies.

You also have the option to import or export your cookies for different purposes.

Cookie Manager Firefox Extension

Many of Cookie Manager’s prominent features are:

  • You can enable or disable the add-on according to your preferences.
  • You can add, edit, or delete cookies.
  • You can recognize and delete the same set of cookies with one click.
  • You can import or export cookies.
  • You can also allowlist cookies.

The Cookie Manager extension can pose a problem when browsing Private Mode on Firefox. This is a serious issue and still needs fixing.

Download Cookie Manager

HTTPS Everywhere

If you are always concerned about the data leak, then HTTPS Everywhere add-on will assure you about the same for life. It encrypts your web no matter where you go or what you browse.

Any website that supports HTTPS will automatically be encrypted once you start using this add-on.

HTTPS Everywhere Add-on for Secured Browsing on Firefox

To name a few of HTTPS Everywhere’s prime features:

  • It encrypts your data whenever you visit a website.
  • It automatically functions on websites with HTTPS.
  • Unlike others, it is easy to use.
  • It rewrites all HTTPS requests.

However, it can consume a lot of memory and start causing problems on your Firefox browser. It may start lagging and slowing down.

Download HTTPS Everywhere

Bottom Line: Best Firefox Developer Add-ons

Mozilla Firefox has been the favorite browser of many people worldwide, including me. It has many brilliant features and works better than the other browsers. Millions of people trust Firefox as their default browser and continue to use it for various purposes.

It has been of great help to people from all walks of life. It is no secret that the add-ons make for more than enough of the features that Firefox lacks. These add-ons are like a blessing to developers who have a lot to achieve in a short period. Henceforth, we have curated this list of add-ons for their use and help. With their merits and demerits mentioned, I am sure you’ll make a wise choice.

These add-ons have greatly helped me as well. As a developer, the Octotree add-on helps me with my coding. Whereas, Ghostery provides me with a distraction-free environment to work in. I am so glad I discovered these add-ons.

Which is your favorite Firefox add-on from the mentioned list? Do you want to add us to any other that you consider best?

Lastly, here are the recommended web browsers for computer and mobile phone that you should give a try.

Chrome WindowsChrome MacChrome iOSChrome AndroidFirefox Linux
Firefox WindowsSafari MacSafari iOSEdge AndroidChrome Linux
Edge WindowsFirefox MacEdge iOSSamsung InternetEdge Linux

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