There has been several blogs that lists the best Firefox extensions that are out there. Since Pingdom are operating in the web performance and monitoring field we decided to make our own list of valuable Firefox extensions.

In this list we don’t cover the well known extensions such as Web Developer Toolbar and Firebug but rather focused on “lesser known” ones that can help development and testing. Extensions that deal with HTML, CSS, SEO and design were also ignored since other blogs have already made good lists of these kinds of tools.

Let’s get on to the list.

YSlow

YSlow has received great attention which is hardly a surprise since it’s such a good tool. It can analyze web sites and give you information about all requests that are made, load time, component sizes and also give you tips on how you can improve the speed of your web site. This extension requires that Firebug is installed.

Jiffy Firefox Extension

Jiffy is a new extension which gives a more detailed view of Javascript time measurements. You can get information of AJAX requests and other Javascript functions. The extension is based on Jiffy-Web Suite. This extension requires that Firebug is installed.

Firecookie

Using Firecookie you can view and manage cookies. It also has a console where you can see when cookies are created, changed or deleted. This extension requires that Firebug is installed.

Live HTTP Headers

Live HTTP Headers as the name says lets you view the headers sent by the web server. This can be useful when debugging web applications. It also lets you edit request headers and replay a request.

HttpFox

HttpFox monitors and analyzes all incoming and outgoing http traffic between the browser and the web server. It displays all request and response headers, sent and received cookies, querystring parameter, POST parameters and response body.

Poster

Poster is a tool for interacting with web services and other web resources and analyze the result. You can make HTTP requests and edit the body and content type and then inspect the result.

DNS Cache

This extension lets you easily disable and enable the DNS Cache in Firefox.

TestGen4Web

TestGen4Web is a tool that lets you record actions in Firefox to a XML file which can later be played back. The output can also be translated into formats so the recorded tests can be processed in other software as automated test scripts.

Selenium IDE

Selenium is a test tool for web applications where Selenium IDE is the recorder, much like TestGen4Web. It can record and playback actions and save the recordings as different scripts.

For more Firefox extensions for web development and design, see the following blogs:

• Top Best 50 Firefox Extensions for web design
• 10 Must Have Web Development Firefox Extensions
• 30+ Firefox Add-ons for Web Developers & Designers

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But while much of the open source community has little love for Microsoft, Microsoft is actually trying desperately to send some love back. The Redmond giant may have its own business reasons for doing so, of course, but that doesn’t change the fact that Microsoft is contributing to open source in more ways than most people are aware of.

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These products have continued to develop at their new homes, but the seed of innovation that sparked an actual, new product came from the outside. The key word here is innovation.

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Here below we have included a quote from Google’s latest SEC filing with some very interesting information about what Google has to say about its competition.

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Big sites and services like Yahoo, Facebook, Twitter and many others rely heavily on open source software to run their operations. Happily, this isn’t a one-way street. They are also giving back to the open source community, not just by contributing to existing projects, but sometimes by open sourcing their own internal projects, giving back something completely new.

And what these popular sites can contribute is often quite valuable. Since they tend to be very large, they run big operations and have been forced to create solutions for scalability and performance problems that most other sites simply don’t have to deal with.

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