More than a dozen Firefox Web development plug-ins are recommended

Development Tools

2. Web Developer 1.1.8
   Https://addons.mozilla.org/en-US/firefox/addon/60
   ByChrispederick
   The Web Developer extension adds a menu and a toolbar with various Web Developer Tools.
   Note: powerful web analysis tools are required by developers.

4. firebug 1.5.0
   https://addons.mozilla.org/en-US/firefox/addon/1843
   firebug integrates with Firefox to put a wealth of development tools at your fingertips while you browse. you can edit, debug, and monitor CSS, HTML, and JavaScript live in any web page... firebug integrates with Firefox to put a wealth of development tools at your fingertips while you browse. you can edit, debug, and monitor CSS, HTML, and JavaScript live in any web page. visit the firebug website for documentation, screen shots, and discussion forums:
   Description: View, edit, CSS, HTML, and JavaScript on the debug page. Powerful development and debugging tools are required by developers.

6. linrlightweb 0.2.1
   https://addons.mozilla.org/zh-CN/firefox/addon/14068
   F * before installation, please confirm that you have installed the firebug plug-in, get firebug visit: http://getfirebug.com/
   1. enable the webpage editing mode and freely edit the webpage-a good partner of Fiddler;
   2. super selector, search for Operation tags;
   3. refresh CSS, no need Refresh the entire page.
   4. quickly set the CSS Sprites background and drag the mouse to get the position.
   5. keep logon status, and the session does not expire; Disable
   6. IE and chrome are released simultaneously.
   Note: very powerful web development tools.

8. View Source char 2.7
   Https://addons.mozilla.org/en-US/firefox/addon/655
   ByJennifer Madden (mm)
   Draws a color-coded chart of a web page's source code.
   Note: the source code is very nice, with hierarchical indentation and different colors.

10. Tamper data 11.0.0
    Https://addons.mozilla.org/en-US/firefox/addon/966
    Use tamperdata to view and modify HTTP/HTTPS headers and post parameters.
    Views the header of a request sent and received by Firefox. You can modify the header before sending a request.

12. Javascript debuger 0.9.87.4
    Https://addons.mozilla.org/en-US/firefox/addon/216
    Venkman is the code name for Mozilla's JavaScript debugger. Venkman aims to provide a powerful JavaScript debugging environment for Mozilla based browsers.
    Note: javascript Debugger in the Firefox environment is a powerful script debugging tool.

14. Live HTTP headers 0.15
    Https://addons.mozilla.org/en-US/firefox/addon/3829
    View HTTP headers of a page and while browsing.
    Note: All HTTP headers are recorded simultaneously on the browser page.

16. Add n edit cookies 0.2.1.3
    https://addons.mozilla.org/en-US/firefox/addon/573
    cookie editor that allows you add and edit" session "and saved cookies.
    Note: view and modify cookies S. it is inconvenient to display cookies of all browsers instead of the current page.

18. XPath checker 0.4.1
    https://addons.mozilla.org/en-US/firefox/addon/1095
    An interactive editor for XPath expressions. choose 'view XPath 'in the context menu and it will show the editor. you can edit the xpath Expression and it incrementally updates the results.
    Note: It is said that XPath can be debugged.

20. Yslow 2.0.6
    Https://addons.mozilla.org/zh-cn/firefox/addon/5369
    Yslow analyzes Web pages and why they're slow Based on Yahoo! 'S rules for High Performance Web sites.
    Note: it can help us analyze why Web pages are slow. It is based on firebug and can also separately browse Web page elements, such as JS and CSS.

HTML Verification

2. HTML validator (based on cse html validator) 1.2.3
   https://addons.mozilla.org/en-US/firefox/addon/887
   validates HTML authentication ents using the cse html validator engine for Windows. requires cse html validator for wi Ndows. The Lite Edition is available for free at http://www.htmlvalidator.com/lite/
   note: the famous cse html validator engine.

4. relaxed the HTML validator 0.9.5
   https://addons.mozilla.org/en-US/firefox/addon/3939
   " relaxed "is a HTML validator which validates HTML documents using it's own schema definitions written in Relax NG with EMB Edded schematron patterns.:
   Note: HTML validation is directly performed on the current page. The interface is clear and intuitive.

6. Total validator 6.2.0
   Https://addons.mozilla.org/en-US/firefox/addon/2318
   ByAndy Halford
   Perform multiple validations and take screen shots in one go. this 5-in-1 validator works with external, internal, or local web pages using the total validator service or local copy of the desktop tool...
   (The current page in the http://www.totalvalidator.com for HTML validation, the output results with the red letter syntax correction, more friendly. However, verification by other websites is slow and the results are not easy to save.

Page Design

1. Measureit 0.3.92
   Https://addons.mozilla.org/en-US/firefox/addon/539
   Draw out a rusers to get the pixel width and height of any elements on a webpage.
   Note: you can measure the length and width of any selected area on the page, which is very helpful to the interface designer.

2. Colorzilla 2.0.2
   Https://addons.mozilla.org/en-US/firefox/addon/271
   Advanced eyedropper, colorpicker, page Zoomer and other colorful goodies...
   Note: You can select a color from the page or color palette and zoom in or out the page.

Seo ads

2. rankquest Seo toolbar 3.9.2
   https://addons.mozilla.org/en-US/firefox/addon/1471
   rankquest SEO (Search Engine Optimization) toolbar provides you quick access to more than 30 intuitive SEO tools. alexa rank and Page Rank provided by Alexa and Google respectively ensures the popularity of the site. once you download and install the SEO toolbar you are only one or two clicks away from carrying out most of your day to day Seo...
   Description: Seo tool plug-in. When you access a page, displays various rankings and Seo information on this page.

4. Adsense pre view 1.5
   Https://addons.mozilla.org/en-US/firefox/addon/2132
   Preview the Google ads that may show on any web page.
   Note: Google ads is displayed on the current page to help determine the ad location.

Other tools

2. Hackbar 1.4.2
   Https://addons.mozilla.org/en-US/firefox/addon/3899
   Simple security audit/penetration test tool.
   Note: various encoding tools for strings are supported: MD5, base64, urlencode, and urldecode.

4. document map 0.6.1
   https://addons.mozilla.org/en-US/firefox/addon/475
   displays the current page's heading structure in the sidebar, allowing rapid navigation...
   Description: Provides page resource structure information ..

6. ie view lite 1.3.5
   https://addons.mozilla.org/en-US/firefox/addon/1429
   

   This is a cut down version of IE view by Paul roub, Which is 47.4 kb. all the same UI and features are there. it has a right click me Nu item to open a page in IE and a list of sites to always open in IE. it can close tabs automatically and send...
   Note: Right-click to open the page in IE to facilitate cross-browser debugging.

8. Timestamp converter 2.0.0
   Https://addons.mozilla.org/en-US/firefox/addon/2063
   Converts dates and timestamps. Context menu option to convert the selected timestamp into a date.
   Note: Apart from conversion from context, you can also manually convert timestamp to date/time.

10. Timestampdecode 0.1.8
    Https://addons.mozilla.org/en-US/firefox/addon/3208
    Treats the selected number as a timestamp and displays a decoded date/time.
    Note: The selected number is converted to date/time as the timestamp.

12. fire encrypter 4.0
    https://addons.mozilla.org/en-US/firefox/addon/2063
    fireencrypter is an Firefox extension which gives you encryption/decryption and hashing functionalities right from your Firefox browser, Mostly useful for developers or for Education & fun...
    description: encrypts text into the ciphertext of various algorithms , and even includes the moles code.

14. add-in-One sidebar
    https://addons.mozilla.org/en-US/firefox/addon/1027
    AIOS lets you open various windows as sidebar panels, and quickly switch between them. so it put an end to the window chaos! In addition to bookmarks and history it opens dialogues such as downloads, add-ons and more in the sidebar.
    Note: Add a toolbar on the left side of the browser to open bookmarks, history, and plug-ins.