Essential Firefox plugins for QA Testers

Firefox is far becoming an important browser for testers engaging in web application domain. With its number of plugins available on the web, this browser's extensibility seems to break the normal stack of a browser's capability, and this proves essential when dealing with web application testing. Following list of plugins are extremely useful for testing web applications. There are plugins useful for security testing, analyzing page source, accessibility, debugging and pretty much everything needed for web application testing. QA tester's productivity will surely be enhanced with some of these plugins.

1. Firesizer 0.92
Provides a menu and status bar to resize the window dimensions to a specific size. This add-on is extremely useful if you want to test how your application will look in different size windows.

2. W3C Page Validator 3.0.0
This little add-on validates a page using the W3C Markup Validation Service. Depending on your context, if your organization is committed to create W3C compliant web applications, this might be very handy.

3. SQL Injection 1.2
This is an excellent tool to help developers in identifying SQL injection vulnerabilities. This add-on transform checkboxes, radio buttons and select elements to an input text box. It makes it easier to test and identify SQL injection vulnerabilities in web pages.

4.QuickRestart 1.1.5
This plugin is useful whenever you need to restart firefox after enabling or disabling an extension, switching to a new theme, or modifying configuration files. This simple extension adds a "Restart Firefox" items to "File" menu. 

5. Firebug
If you are working in web application domain, I am sure you are already familiar with this add-on. Firebug, along with the development toolbar are absolute minimum your firefox should have if you are working in web application testing domain.

6. Regular Expression Tester
This plugin offers developers functions for testing their regular expression. This includes options like case sensitive, global and multiline search, color highlighting of found expressions and of special characters, a replacement function incl. backreferences, auto-closing of brackets, testing while writing and saving and managing of expressions.

7. HttpFox
This add-on is an amazing tool if you want to dig deeper into http request / response and analyze all the traffic. Using this add-on, you can get information about request / response header, sent and received cookies, Querystring parameters, POST parameters and Response body.

8. Web Developer Toolbar
This plugin along with the firebug are must have extensions if you are working/testing in web application domain. These extensions are complete toolset and probably require separate articles to explain their capabilities.

9. Add N Edit Cookies
There are very few applications which does not use cookies these days. This little add-on allows you to add / edit cookies and test how your application will respond to changes in the cookies setting.

10. Link Evaluator 0.9.9.7
Link Evaluator follows every link on the page, and evaluates both the HTTP status code and the page contents returned. It attempts to distinguish between various results such as broken links (404), network time-outs, authentication failure, and 'incorrect' content for the given URL.

11. MeasureIt 0.3.8
If you have a design team which is very particular about the size of every element, than this little add-on can be used to test hight and width of all the elements. It draws a ruler around any element and shows hight / width of the element.

12. YSlow 2.0.0b3
YSlow analyzes web pages and suggests ways to improve their performance based on a set of rules for high performance web pages. YSlow is a Firefox add-on integrated with the Firebug web development tool. YSlow grades web page based on one of three predefined ruleset or a user-defined ruleset. It offers suggestions for improving the page's performance, summarizes the page's components, displays statistics about the page, and provides tools for performance analysis.

13. FireShot 0.69
FireShot can be handy in situations where you want to take screen shot of your web application. It even allows you to write comments, highlight specific element of your application and so on.

14. URLParams 2.2.0
This little add-on make it convenient to analyze GET and POST parameters of the current website in the sidebar. You can even change their values, add new parameters etc.

15. Tamper Data 10.1.0
Tamper Data allows you to view and modify HTTP/HTTPS headers and post parameters. You can use it to test security of your web applications by modifying POST data and analyzing how your application will respond to those changes.

16. View Dependencies 0.3.3.0
This is an extremely useful add-on if you want to figure out what are all the files / images etc. are getting downloaded for every page, how much time they are taking and many such details.

Hope this list proves useful to every testers working on web application platform. Feel free to add more useful plugins you have used that are not listed above in the comment area.