1. Open up your Applications folder and find your old version of Firefox.
2. Right click -> Get Info.
3. Rename to “Firefox36.app”.
4. Download Firefox 4.0 and install as normal.

Voilà! You now have more than one Firefox browser to play with.

That was really simple huh? If someone knows how to do this on the Windows and Linux side, I would love to hear how.

Google’s addition of a page speed signal to its search rankings algorithm officially links performance with search engine marketing. The loading speed of a web page affects user psychology in a number of ways, and now it can effect its rankings as well.

From the Google Webmasters’ Blog:

Speeding up websites is important — not just to site owners, but to all Internet users. Faster sites create happy users and we’ve seen in our internal studies that when a site responds slowly, visitors spend less time there. But faster sites don’t just improve user experience; recent data shows that improving site speed also reduces operating costs. Like us, our users place a lot of value in speed – that’s why we’ve decided to take site speed into account in our search rankings. We use a variety of sources to determine the speed of a site relative to other sites

If you are a site owner, webmaster or a web author, there are some free tools that you can use to evaluate the speed of your site and therefore improve site performance:

• Page Speed, an open source Firefox/Firebug add-on that evaluates the performance of web pages and gives suggestions for improvement.
• Yahoo! YSlow a Firefox/Firebug Add-on that analyzes web pages and suggests ways to improve their performance, based on a set of rules for high performance web pages.
• WebPageTest shows a waterfall view of your pages’ load performance plus an optimization checklist.
• BrowserMob a tool for website performance monitoring and alerting.
• Chrome Developer Tools that let you edit, debug, and monitor CSS, HTML, and JavaScript live in any web page. You can also use them to optimise web page performance by profiling CPU and memory usage.
• Google’s Webmaster Tools, in the Labs menu, Site Performance shows the speed of your website as experienced by users around the world.

Other tools, including those for web debugging (Charles and Fiddler) and resource optimisation (Smush It and YUI Compressor), can be found on Google Code.

Google’s announcement of adding a page speed signal into its search rankings algorithm will in the long term will force the hand of website owners to increase the performance of their websites. This can only be a good think for user experience. With time and investment, the frustration of slow-loading websites will be banished to the past.

But what is a User Agent? A User Agent is the client application used with a particular network protocol; the phrase is most commonly used in reference to those which access the Web. Web user agents range from web browsers and e-mail clients to search engine crawlers (spiders), as well as mobile phones, screen readers and braille browsers used by people with disabilities. When Internet users visit a web site, a text string is generally sent to identify the user agent to the server. This forms part of the HTTP request, prefixed with user-agent: and typically includes information such as the application name, version, host operating system, and language. Bots, such as web crawlers, often also include a URL and/or e-mail address so that the webmaster can contact the operator of the bot.

By simply typing about:version into Chrome’s address bar you will be presented with the following information:

Google Chrome
0.2.149.29 (1798)
Official Build
Google Inc.
Copyright © 2006-2008 Google Inc. All Rights Reserved.
Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US) AppleWebKit/525.13 (KHTML, like Gecko) Chrome/0.2.149.29 Safari/525.13

As you can see Chrome’s version information provides limited detail about the browser. The last line is the important one. It is the HTTP User-Agent header:

Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US) AppleWebKit/525.13 (KHTML, like Gecko) Chrome/0.2.149.29 Safari/525.13.

If you know the RFC 2616 specification on the HyperText Transfer Protocol — which incidentally, I gladly don’t — you would know that the User Agent, or more formally, product token, should be short and to the point:

Product tokens SHOULD be short and to the point. They MUST NOT be used for advertising or other non-essential information. Although any token character MAY appear in a product-version, this token SHOULD only be used for a version identifier (i.e., successive versions of the same product SHOULD only differ in the product-version portion of the product value).

Clearly this isn’t the case! One of Google’s reason’s behind creating the Chrome browser was to start afresh. It would have therefore been truely amazing if they had made the string simply Chrome/0.2.149.27.

Unfortunately, browser sniffing makes an ever-growing UA string the path of least resistance for browser vendors.

So, what does Chrome’s User Agent string actually mean:

• Mozilla/ – This means that browser has the kind of capabilities that Netscape 1.1 had compared to Mosaic and Lynx.
• 5.0 – This means that the browser engine is from the post-Browser War Web Standards era as opposed to being from the Browser War era.
• (Windows; – This means that general windowing system flavor the browser runs on is Windows (as opposed to, for example, Apple and X11).
• U; – This means that the browser has at least the level of cryptographic capability / encryption strength that U.S. versions of browsers had in the late 1990s.
• Windows NT 6.0; – This indicates the operating system the browser is running on. In this instance, the browser is running on Vista.
• en-US) – This indicates the user interface language of the browser (U.S. English in this case). This may be used to choose between different content languages even though HTTP has a different header for that purpose.
• AppleWebKit/ – This indicates that the engine of the browser is WebKit as opposed to being Gecko. Developers should not do user agent sniffing as a rule, but if they still do, this is what they should be sniffing.
• 525.13 – This is the WebKit version from which Chrome branched its copy. Site admins could use this to detect old versions with known bugs.
• (KHTML, like Gecko) – This introduces the substring Gecko into the UA string while pointing out to human readers that Webkit was forked from KHTML. Without this substring, Chrome might be put in the same category as IE and Netscape 4.
• Chrome/ – This string identifies the browser as actually Google Chrome.
• 0.2.149.27 – This is the Chrome version. This could be used to detect old versions with known bugs.
• Safari/ – This means that the browser is like Safari as opposed to being like Firefox.
• 525.13 – This just repeats the WebKit version in order to have some version but not the irrelevant Safari.app version.

Join the movement SaveTheDevelopers.org.

Here is a list of the Firefox extensions I utilise in my day-to-day work:

ColorZilla

https://addons.mozilla.org/firefox/271/

Advanced Eyedropper, ColorPicker, Page Zoomer and other colorful goodies.

With ColorZilla you can get a color reading from any point in your browser, quickly adjust this color and paste it into another program. You can Zoom the page you are viewing and measure distances between any two points on the page. The built-in palette browser allows choosing colors from pre-defined color sets and saving the most used colors in custom palettes. DOM spying features allow getting various information about DOM elements quickly and easily.

Firebug

https://addons.mozilla.org/firefox/1843/

FireBug lets you explore the far corners of the DOM by keyboard or mouse. All of the tools you need to poke, prod, and monitor your JavaScript, CSS, HTML and Ajax are brought together into one seamless experience, including a debugger, an error console, command line, and a variety of fun inspectors.

FireFTP

https://addons.mozilla.org/firefox/684/

FireFTP is a free, secure, cross-platform FTP client for Mozilla Firefox which provides easy and intuitive access to FTP servers.

Along with transferring your files quickly and efficiently, FireFTP also includes more advanced features such as: directory comparison, syncing directories while navigating, SSL encryption, file hashing, and much more.

HTML Validator

http://users.skynet.be/mgueury/mozilla/

HTML Validator is a Mozilla extension that adds HTML validation inside Firefox and Mozilla.
The number of errors of a HTML page is seen on the form of an icon in the status bar when browsing.
The details of the errors are seen when looking the HTML source of the page.

The extension is based on Tidy. Tidy, was originally developed by the Web Consortium W3C. And now extended and improved by a lot of people. Tidy is embedded inside Mozilla/Firefox and makes the validation locally on your machine, without sending HTML to a third party server.

IE Tab

http://ietab.mozdev.org/

This extension embeds Internet Explorer (IE) in a Mozilla/Firefox tab, which allows you to view your work in IE without launching a separate window.

LinkChecker

https://addons.mozilla.org/firefox/532/

Checks the validity of links on a web page.

MeasureIt

https://addons.mozilla.org/firefox/539/

Draw out a ruler to get the pixel width and height of any elements on a webpage.

SEO for Firefox

http://tools.seobook.com/firefox/seo-for-firefox.html

This tool was designed to add more data to Google and Yahoo! to make it easier to evaluate the value and competitive nature of a market. SEO for Firefox pulls in many useful marketing data points to make it easy get a more holistic view of the competitive landscape of a market right from the search results. In addition to pulling in useful marketing data this tool also provides links to the data sources so you can dig deeper into the data.

Server Spy

https://addons.mozilla.org/firefox/2036/

Server Spy indicates what brand of HTTP server (eg. Apache, IIS, etc.) runs on the visited sites. When a tab is selected, the corresponding server name is shown on the right-hand side of the browser’s status bar.

Snapper

https://addons.mozilla.org/firefox/2703/

People often take screenshots of web pages for miscellaneous reasons – when designing a page, debugging a web application, or even for graphical reference. Usually, though, only a portion of the screenshot is actually relevant to the user’s purpose, leading to a large portion of the image getting cropped. This can be time consuming, and annoying at times.

Snapper allows users to designate an area of a web page for a focused snapshot, cutting out the additional work needed for cropping unecessary information.

Web Developer

https://addons.mozilla.org/firefox/60/

http://chrispederick.com/work/webdeveloper/

The Web Developer extension adds a menu and a toolbar to the browser with various web developer tools.

Here is a list of other extensions I find useful:

CustomizeGoogle
Gmail Space
Google Notebook
GooglePreview
SessionSaver
Tails Export