firefox add ons for developers

The Best Firefox Add-ons for Developers: 30+ Tools for Programmers

Angela Stringfellow Developer Tips, Tricks & Resources Leave a Comment

Hey…remember Firefox? Google Chrome is now king of the browser hill, but Firefox is still chugging along and is actually still the best browser for web app developers to use. Sure it’s a little slow and hard on memory, but its customization options can’t be beaten. We’ve listed a few of our favorite Firefox add-ons that make our lives as developers a little easier, and hopefully, they’ll save you a bit of time and frustration, as well. From tools designed to meet web developers’ needs to debugging add-ons, tab management tools, password management tools, and more, we’ve rounded up 35 time-saving tools to make your web development work more seamless.

No worries, no SPAM. Opt-out anytime.

While this post was originally published in a previous year, we’ve recently updated it to eliminate add-ons that are no longer available, include the most recently available information on features and functionality, and replace tools with ratings of 3/5 stars or lower with higher-rated add-ons. All reviews listed with their respective add-ons are taken directly from the Firefox add-on pages, so please excuse the spelling and grammar. Also, note that all Current Ratings are the current overall average rating for each add-on as of the most recent update of this list (in March 2017).

Best Firefox Add-ons – Web Developer Tools

This is where Firefox truly shines. There are a number of Add-ons available for just about any type of web development, and added bonuses like direct FTP capabilities within the browser!

Fire FTP

best firefox add-ons for developers

Current Rating: 4/5 stars

A fast, secure, and cross-platform FTP/SFTP client right in your browser, Fire FTP provides seamless access to your FTP/SFTP servers. It’s worth noting that some users are reporting some difficulties in recent reviews with data connection errors when uploading, problems with the drag-and-drop file feature, and some compatibility issues with a recent version of Firefox. However, the vast majority of reviewers award FireFTP a perfect, 5-star rating, and one reviewer points out that updating to 2.0.31 and Firefox 51 solves these issues.

Add-on User Review:

by Joe on September 16, 2016 – permalink

I’ve been using this plugin for some years now and I’ve never had any issues with it. What can I say… It just works.

This review is for a previous version of the add-on (2.0.28).

Web Developer

best firefox add-ons for developers

Current Rating: 5/5 stars

Adds a wealth of great web development tools to your browser, Web Developer is an extension available not only for Firefox but also Chrome and Opera, and it will work on any system supported by these browsers, including Windows, OS X, and Linux.

Add-on User Review: 

A must for developers

SQLite Manager

best firefox add-ons for developers

Current Rating: 4/5 stars

Manage SQLite databases right from your browser with SQLite Manager, which offers tons of features including an intuitive hierarchical tree showing database objects, helpful dialogues for managing tables, indexes, views, and triggers, a dropdown menu that helps with syntax, enabling you to write SQL easier, intuitive access to functions and common operations through the menu, toolbars, buttons, and context-menu, and more.

Add-on User Review:

by Calvin on June 27, 2016 – 

Very simple, easy to use and functional tool to manage SQLite databases, I have been using it for a while and I really like it. One little complaint I would have however is that it currently does not support right and full joins, which I unfortunately only found out about when I recently needed to use a right join but couldn’t. Other than that, this is great and when those operations are suported this will be the perfect SQLite management tool.

FirePHP

best firefox add-ons for developers

Current Rating: 4/5 stars

FirePHP makes it possible to quickly and easily debug code without interfering with live content. It’s the perfect Firefox add-on for AJAX developers that allows you to log to your Firebug Console using a simple PHP method call.

Add-on User Review:

Very useful and well working addon, it simplifies debugging of PHP code very much.
I only need two more features in it, I think that with them FirePHP will become THE ultimate debugging addon:
1. The ability to show only FirePHP debug messages in FireBug console. In most cases console is filled with non-critical warnings, but if you disable them to view only useful information, FirePHP output disappears.
2. And the ability to search in Variable Viewer. If variable contains many fields and nested objects, it takes much time to find the needed part, as Firefox search works only in underlying window contents or in Firebug console.

Anyway, great addon and thank you for your work and time!

Flash Debugger

Flash Debugger

Current Rating: Not yet rated

Flash Debugger is the successor to FlashFirebug and is an addition to Firefox’s built-in dev tools, offering the ability to debug any AS3 Flash on the web. With Flash Debugger, you can inspect the DisplayList, change properties on the fly, and see warnings, errors, and traces directly within the Flash Debugger extension.

Note: As this is a successor product to a previous extension, there are not yet any user reviews at the time of this writing, although this extension already has 2,450 users.

JavaScript Deobfuscator

best firefox add-ons for developers

Current Rating: 5/5 stars

Watch and debug JavaScript as it is compiled/executed on the page with JavaScript Deobfuscator, which shows you all the JavaScript that runs on a page — even code that’s obfuscated and generated on the fly. It’s a valuable tool even when you’re working with websites that aren’t using obfuscation.

Add-on User Review:

Very useful to see how things work. A must have for JS developers. There is much space for improvements, but this is a new beginning. Keep up the good work!

FireQuery

best firefox add-ons for developers

Current Rating: 4/5 stars

Created specifically to help jQuery Developers, FireQuery is a collection of jQuery enhancements for developers. Built on top of native Firefox developer tools, FireQuery presents jQuery expressions nicely in the Firebug Console, presents jQuery data in the inspector panel, and enables you to inspect jQuery data details. It also includes jQuerify, enabling you to inject jQuery into any page.

Add-on User Review:

I have been developing with Angular.js lately and noticed that there was a strange bug which made angular.js stop working when i went to look inside the console (firebug). I then got this error TypeError: this.__FireQueryShared is undefined which I then turned off FireQuery and the bug was prevented. I don’t want to turn FireQuery off though cause I love it!

This review is for a previous version of the add-on (1.4.1.1-signed).

Empty Cache Button

best firefox add-ons for developers

Current Rating: 4/5 stars

Quickly and easily empty your browser’s cache with the click of a button with Empty Cache Button, including an optional notification of success (although Mac users will require Growl), an optional reload of all tabs or active tabs, and an optional automatic cache clearing for Firefox 31.0 and earlier. Note that beginning with Firefox 53, Empty Cache Button is built with the new WebExtensions API, and for older versions of Firefox, you should use version 2.7.1.

Add-on User Review:

It does what it says; and it also allows to refresh the current page on clicking the button, which is great because it makes the whole process still faster.
Thanks!

Wappalyzer

best firefox add-ons for developers

Current Rating: 4/5 stars

Identify how a website has been built and the systems it runs on with Wappalyzer. It detects a variety of underlying technologies used for websites including content management systems (CMS), eCommerce platforms, analytics tools, JavaScript frameworks, and more. You can check out a full list of applications Wappalyzer detects here. This extension is also available for Chrome.

Add-on User Review:

I have been using this for over 3 years and I love it. Absolute developer must-have!

RESTClient

RESTClient

Current Rating: 4/5 stars

With RESTClient, you can construct custom HTTP requests to directly test requests against a server. This add-on supports all HTTP methods RFC2616 (HTTP/1.1) and RFC2518 (WebDAV).

Add-on User Review:

Have been using this for a couple of years now for testing our REST APIs, using POST, OAuth and JSON content, works perfectly, easy to use, best tool I came across!

JSONView

JSONView

 

Current Rating: 5/5 stars

With JSONView, you can view JSON documents right in the browser with ease. Rather than Firefox prompting you to download the file, documents are shown in the browser similar to the way XML documents appear. The document is formatted and highlighted with collapsible arrays and objects, and even if the JSON document contains errors, this add-on will still display the raw text.

Add-on User Review:

Thank you for a great extension, and thanks for making it easy to add new content types (I needed “application/vnd.api+json”). Didn’t even have to restart. I’ve just build a json API for an important government dataset, and you’ve helped.

Best Firefox Add-ons – Web Development Testing

You can also use Firefox Add-ons to debug and test all your development work!

FoxyProxy

best firefox add-ons for developers

Current Rating: 4/5 stars

FoxyProxy provides advanced proxy management for Firefox, completely replacing Firefox’s limited proxying capabilities. It automatically switches an Internet connection across one or more proxy servers based on URL patterns. If you need a simpler add-on with less advanced configuration options, you should consider FoxyProxy Basic.

Add-on User Review:

I use multiple proxy! With this add-in is automatically switched without manual intervention. I am very grateful to this add-in!

This review is for a previous version of the add-on (4.5.7).

User Agent Switcher

best firefox add-ons for developers

Current Rating: 4/5 stars

User Agent Switcher adds both a menu and a toolbar button to quickly switch your browser’s user agent. User Agent Switcher has more than 310,000 users, and about half of the extension’s 268 reviewers give it 5 stars.

Add-on User Review:

This add-on has saved me more than once when needing to get downloads for different platforms.

The only feature I find lacking is an automatic page reload when the user agent has been switched. Not a big deal, but would save a little bit of time.

HttpFox

best firefox add-ons for developers

Current Rating: 4/5 stars

HttpFox analyzes both incoming and outgoing HTTP traffic between browser and server, aiming to bring the functionality of tools such as HttpWatch and IEInspector to the Firefox browser, providing a wealth of information with each request including request and response headers, sent and received cookies, Querystring parameters, POST parameters, and response body.

Add-on User Review:

Thank You! This is Great Application, but there is need as air few things:

– Searching by content/all data (not only by URLs)
– Deleting/marking some lines. It’s hard to operate with results without it

or just All Data Export in some understandable format – it would be even better.

Poster

best firefox add-ons for developers

Current Rating: 4/5 stars

Interact with web services and send HTTP requests to view the results with Poster, a great add-on for debugging that allows you to set the entity body and content type for requests. The full Poster code is available at Google Code.

Add-on User Review:

Good tool. It can have performance issues at times, though — such as when GETting a large chunk of JSON data.

To robertvazan and others who installed it in a recent Firefox but can’t figure out how to access it, here is how:

Click the Open Menu button (far right)
Click Customize
Click Show/Hide Toolbars
Select Menu Bar
Close the Customize tab

Now you can access Poster through the Tools menu bar dropdown, as before. Enjoy!

HTML Validator

best firefox add-ons for developers

Current Rating: 4/5 stars

HTML Validator adds HTML validation inside Firefox, showing you the number of HTML errors on a page in the form of an icon in the status bar. Details of the errors are shown in the HTML source of the page. Note that for online HTML 5 validation, you’ll need 0.962.

Add-on User Review:

I’ve been testing HTML Validator 0.9.7.4 Beta with no problems on the version of SeaMonkey mentioned below, comparing “Tidy” results with “SGML” results. In particular the “Tidy” version found attribute errors (including quite a number of mismatches due to typos between the name= and id= attributes of <a> tags). 🙂

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:50.0) Gecko/20100101 Firefox/50.0 SeaMonkey/2.47a1
Build identifier: 20160625075045
http://hg.mozilla.org/mozilla-central/rev/0e073f5ca38a002d43e92016ee40d686da4a0534
http://hg.mozilla.org/comm-central/rev/ab9359275942

Great that it has ceased being “Windows-only”.

P.S. One unclosed <a> tag caused several “anchor already defined” warnings, but once I had noticed and fixed the error the spurious messages disappeared.

Modify Headers

best firefox add-ons for developers

Current Rating: 4/5 stars

Great for mobile web development, HTTP testing, and privacy Modify Headers enables you to add, modify, and filter HTTP requests sent to web servers. (Check out this guide on HTTP request headers from W3.org.)

Add-on User Review:

Simplicity to set up and use, works perfectly. Only drawback is you have to disable filtering such as Privoxy which strips out referrer headers, leaving you open to ad’s and spam cookies.

IE Tab V2

best firefox add-ons for developers

Current Rating: 4/5 stars

Test your web app or website on IE with IE Tab V2. This is an updated version of the original IE Tab, enabling you to embed IE within a Firefox tab and offering support for Firefox 3.6. The developers note that they’ll continue to update this add-on with new features and enhancements. The source code is also available on GitHub.

Add-on User Review:

Works just as it should.
I did switch the compatibility to IE9 instead of the default IE7, but thats it.
Great addon! Thanks for this!

Win10Pro / FF47.0.1 / x64

Greasemonkey

Greasemonkey

 

Current Rating: 4/5 stars

Greasemonkey lets you control the way a web page displays and behaves using small bits of JavaScript. Make your browsing experience seamless, enjoyable, and frustration-free with the aid of Greasemonkey’s easy-to-use features. You can even write your own scripts (visit the Greasmonkey Wiki for more details), or check out the existing scripts you can put to use to control your favorite sites here.

Add-on User Review:

Greasemonkey is good for devs to try new things, mod environment.

HackBar

HackBar

 

Current Rating: 4/5 stars

A simple security audit and penetration testing tool, HackBar is a must-have for any developer wanting to ensure the security of their work. It’s not a tool for executing standard exploits, and it won’t teach you how to hack a website, but it will help you test SQL injections, XSS holes, and site security. You can get the source code at GitHub.

Add-on User Review:

Thanks for this addon. It’s very convenient for pentest. Just missing the ability to emulate ajax requests when using with GET or POST. When a script verifies that the xmlhttprequest object was sent, it isn’t possible to use the hackbar for the test.

Best Firefox Add-ons – Screenshots

FireShot Pro

best firefox add-ons for developers

Current Rating: 5/5 stars

Quickly grab a screenshot of an entire web page and annotate it with FireShot Pro, a useful add-on that quickly captures and saves screenshots (as an image or PDF), allowing you to send screenshots to your clipboard, print them, annotate, upload, and emails them from a single tool. Note that certain features (annotating, uploading, and emailing) only work on Windows OS.

Add-on User Review:

Excellent add on- works very well. Would actually purchase pro version and give 5 stars if had firefox 64bit support. But alas- and this app is the only reason I still run firefox x86

Nimbus Screen Capture

Nimbus

 

Current Rating: 4/5 stars

Nimbus Screen Capture lets you screen capture entire web pages or selected regions, as well as whole browser windows. You can edit them, save locally or to Google Drive, annotate screenshots with different tools, and upload and share your screenshots for easy collaboration and other uses. There’s also a Chrome version of this add-on, and you can check out the quick guide here.

Add-on User Review:

Although I think the quality of screenshots could be better. For large pictures with text, the quality isn’t as good as when you zoom in the original page. Keep up the good work!

Lightshot

Lightshot

Current Rating: 5/5 stars

Lightshot makes it easy to take quick screenshots of any selected area on a web page. Simply click the Lightshot icon in the toolbar or status bar, select the area you want to capture, and choose “Save” or “Upload to server.” There are also a few shortcuts you can use to make capturing screenshots with Lightshot even simpler.

Add-on User Review:

Clean, easy & simple, no bullshit, does what I says it does. It allows to capture, save in one click, email, and edit printscreens from your screen. Great for, e.g., making printscreens of selected items or specific stuff when you don’t want the whole contents of your screen in the picture.

I wonder why on earth are heaps of people are (still) using add-ons like Easy Screenshot, when there is Lightshot?

Best Firefox Add-ons – Time-savers and Shortcuts

Speed up your browsing and keep yourself on task with these great Firefox Add-ons.

ColorZilla

best firefox add-ons for developers

Current Rating: 4/5 stars

Get the color reading from any point within your browser, quickly adjust the color to your preferences, and paste it into another program with ColorZilla. While color-picking is ColorZilla’s core functionality, it offers a number of other useful features such as an eyedropper tool for grabbing the color from a single pixel on a web page, a CSS gradient generator, a web page color analyzer to get a palette based on any website, and more. Note: Many reviewers express frustration with a recent update, which the developers will hopefully rectify soon.

Add-on User Review:

A very useful program for graphics and color designers. The best one,I dare say!

This review is for a previous version of the add-on (2.8.2). This user has a previous review of this add-on.

Fire Gestures

best firefox add-ons for developers

Current Rating: 4/5

Set up mouse gestures for quick shortcuts within your browser with Fire Gestures, a customizable extension that enables you to execute different commands and user scripts with six types of gestures: mouse gestures, wheel gestures, rocker gestures, keypress gestures, tab wheel gestures, and swipe gestures.

Add-on User Review:

It makes using Firefox so convenient and easy. I can’t use any other browser. I tried becoming a Google Chrome guy, but without Fire Gestures, the experience sucked. This app is the reason I came back. I can do everything I need with the swipe of my mouse. The gestures I use most are save, close, open to front, open to back, last page, and go forward.

Video DownloadHelper

Video DownloadHelper

Current Rating: 4/5 stars

Strip almost any video from the web with Video DownloadHelper, an easy-to-use add-on that makes it easy to download and convert videos from hundreds of sites with YouTube-like functionality. But that’s not all: You can also record Twitter Periscope and use it to capture full browsing sessions. Check out the user manual here.

Add-on User Review:

high performance in media detecting, easy to use.

Session Manager

best firefox add-ons for developers

Current Rating: 4/5 stars

Save and restore any browsing session for later use with Session Manager, either when you want it to or automatically on startup, after crashes, or periodically. Additionally, Session Manager can save the state of open windows individually. Check out the complete user guide for details on all options here.

Add-on User Review:

Been using this wonderful add-on for about two years; without doubt, it is on my exclusive “must have” list. Nice surprise is that it also saves ALL open tabs, not just the current page. Very useful in daily Bible reading while researching and examining several commentaries and concordances. Thank you. God Bless!

AutoPager

AutoPager

Current Rating: 4/5 stars

Automatically loads the next page when you reach the bottom of a page with pagination. It works across a variety of sites including Google and Yahoo, works well with most other add-ons (such as AdBlock Plus, WOT, and most of the Greasemonkey scripts), and offers a Lite version for users who want more basic functionality. Note that there are some recent reviews indicating that this add-on doesn’t work with the latest version of Firefox, but it’s still usable for those using older versions (at least until the developer decides to release an update).

Add-on User Review:

brilliant, although it doesn’t always work and sometimes creates issues

MeasureIt

best firefox add-ons for developers

Current Rating: 4/5 stars

Draw a box on any page to measure an element’s dimensions with MeasureIt, a handy add-on for checking the width, height, or alignment of any page element in pixels.

Add-on User Review:

This extension does what it needs to do… when it works. I am a developer, and currently use FIREFOX DEVELOPER EDITION. This extension does not work in FDE for some reason. So I have to give it a low score. Fix it, and you got 5 stars, baby!

EDIT… Seems to be working SOMETIMES in FDE now. Still checking how stable it is. 4 stars. Once I confirm stability on all pages… you got 5! 🙂

TinEye Reverse Image Search

best firefox add-ons for developers

Current Rating: 4/5 stars

TinyEye is a helpful reverse image search engine, adding a context menu that helps you find the source of any image and see if there are more sizes available. It was the first image search engine on the web that uses image identification technology instead of keywords. Adding tens of millions of new images to its database every week, TinyEye maintains a feed with its ongoing updates here, and if you’re so inclined, check out TinyEye’s blog.

Add-on User Review:

TinEye is a small company but they are doing an outstanding job. I found that in at least half of my reverse searches TinEye outperforms Google. Very useful add-on when it comes to tracing the real origins of images for research projects and making sure they can be reused.

LastPass

best firefox add-ons for developers

Current Rating: 4/5 stars

Manage all your passwords in one, secure place with LastPass, a password manager that’s earned itself a reputation for being one of the easiest-to-use, robust password management tools available. It’s an award-winning password keeper that provides you with secure access from every computer and mobile device by saving, encrypting, and backing up all your login credentials automatically, syncing your password data across all devices, and leaving you with a single, strong password to remember to make your life exponentially simpler. Note: Some reviewers are reporting some issues with recent updates and certain services.

Add-on User Review:

I use multiple browsers, and coordinating my saved passwords between them all was formerly a pain, but LastPass makes this much easier and its encryption gives me confidence that my credentials are secure.

Ghostery

Ghostery

Current Rating: 5/5 stars

If you want to go incognito as you browse the web and substantially boost your browsing speed, Ghostery is the add-on for you. Ghostery enables you to make informed decisions about the data you choose to share with the websites you visit, providing a cleaner, safer, and faster browser experience as you work.

Add-on User Review:

Ghostery is aimed at the paranoid among us. It’s designed to inform a user about the trackers that are following her as she browses a site. What it does well is provide an unobtrusive set of notifications and graphics about the technologies working behind the scenes to show ads, track clicks, integrate social media, and monitor the site’s engagement. Honestly, without it I would have no clue by whom (and where) I’m being tracked. Even beyond that, though, it gives you easy, custom control over which trackers to trust and when. I can tell it to block a tracker on a single site, or multiple ones. I could even go dark, blocking all of the trackers Ghostery knows of and any new ones it finds.

But as much as it informs and reassures, a few things do trouble me. Given that it is an add-on aimed at security, I was expecting that the full functionality would be available without any registration. Unfortunately, some of Ghostery’s advanced features are hidden behind a login wall (albeit a free one). More to the point, the add-on comes with “page and tracker data” sharing automatically enabled, rather than defaulting to privacy and letting users freely consent to that sharing. I’m sure I’m not alone in worrying what the folks at Ghostery are doing with that data.

For better or for worse, this add-on will open your eyes about the zoo of data-hungry trackers following your every click.

Tab Mix Plus

Tab Mix Plus

 

Current Rating: 4/5 stars

Tab Mix Plus is the ultimate tab management add-on for Firefox, offering a variety of features such as duplicating tabs, controlling tab focus, tab clicking options, the ability to undo closed tabs and windows, and more. Additionally, Tab Mix Plus includes a full-featured session manager. Note that for users of Firefox Beta, Aurora or Nightly, the latest Tab Mix Plus development build is recommended. Change logs are available here, and if you need assistance, check out the help forum.

Add-on User Review:

The fact that the developers have kept this addon up to date through all these major browser changes is commendable. I’ve been using this addon since its inception in 2005 . I can’t imagine Firefox without this addon. There’s been dozens of fresh installs and this is one of the first addons I install.

It simply makes browsing multiple tabs such a convenience. Don’t get me wrong “modern day” Firefox tab management is serviceable but back in the day this addon was an absolute must have. TMP still packs a lot useful features that Firefox doesn’t include.

Couple TMP with Tab Groups and you’ve got yourself a real powerhouse.

All-in-One Sidebar

All-in-One Sidebar

 

Current Rating: 5/5 stars

All-in-One Sidebar enables you to open several windows as sidebar panels and easily switch between them. It opens bookmarks and history as well as dialogues such as downloads, add-ons, page info, error console, and more — all in the sidebar. It won’t obstruct your view, either: simply show or hide it with a switch. Plus, you can configure this add-ons behavior on browser startup or in full-screen mode. Get more info on the many features of this add-on here.

Add-on User Review:

I have used AIOS for years and cannot imagine not having it. The ease of opening it by just touching left of screen with mouse is great now – genius all those years ago. It acts like a split screen and is far better than using the bookmarks, history, ad-dons etc drop down menus. There is a great support site and Ingo is a dedicated developer. I always give money when I can.

Resurrect Pages

Resurrect Pages

 

Current Rating: 5/5 stars

Broken links and dead pages are frustrating for users and developers alike. Thanks to Resurrect Pages, you can resurrect and view pages long given up for dead. This handy add-on searches the four main page cache/mirrors including Google Cache, The Internet Archive, WebCite, and archive.is to bring most pages back from the dead (but not all, as not all pages are cached, of course). The source code is available on GitHub.

Add-on User Review:

Works beautifully at streamlining something you may find yourself doing frequently in research – resurrecting pages.

Let us know your thoughts on Chrome vs Firefox for web development use in the comments below!