What Are Alternatives to Extjs

Are there alternatives to the Ext.js JavaScript GUI Library?

List of some Javascript GUI libraries (not ordered):

jQueryUI
jQuery Tools
YUI
MochaUI (based on Mootools)
Dojo

Freeware Ui designer for alternatives-to-extjs frameworks

In general, you might check out this post:
HTML/JavaScript UI widgets GUI builder

Consider while looking at different tools that some might require special server back-ends. qooxdoo as a toolkit is all client-side.

The rest of this post concerns only qooxdoo and I don't think there are any mature ones available for qooxdoo right now. At least, there are none that are on par with the likes of the experience of developing in Visual Studio and with WinForms (as simply a comparison.) There are some early immature tool attempts at doing similar things, but they still will require a good understanding of qooxdoo and form placement. This is not a complete list:

qooxit: This is a project by Derrell Lipman who is very active as part of the qooxdoo development, but I'm not sure what has become of the future of this project. http://qooxdoo-contrib.svn.sourceforge.net/viewvc/qooxdoo-contrib/trunk/qooxdoo-contrib/qooxit/
jsqt: Uses Qt's .ui files and translates them. I have not used this and my guess is it has many limitations. http://qooxdoo.org/contrib/project#jsqt
Qooxdoo.Net: Uses Visual Studio to design the UI, but the project looks dead. http://sourceforge.net/projects/qooxdoonet/

I think there were also some attempts to put a WYSIWYG designer in front of the XML to qooxdoo tool called QxTransformer, http://qxtransformer.org/ but I may be confusing my projects.

Note that the qooxdoo license is dual licensed to LGPL/EPL. If you are working in a commercial environment some corporations are skittish of anything that isn't MIT or BSD licensed. I mention this in regard to your reference to the "free and open source" alternatives. While I firmly believe the intention of the application of LGPL/EPL is to allow us developers to do whatever we want with our creation as long as we contribute back to any enhancements to the qooxdoo libraries, corporate lawyers are afraid of nothing specific in writing. If you are doing this for commercial organization do your homework first. I had wanted to use qooxdoo for a project, but was prevented because of the license and my companies leaning toward MIT/BSD only open source licenses.

As a library goes, I think qooxdoo is the most feature complete and best structured. It is well documented though it does come with a learning curve. However, examples abound and the forum is very responsive. If there is any criticism about qooxdoo it might be that it is a heavier weight (size) library so that the final compiled javascript is often large (500-700k). For complex applications it can be a bit too intensive for smart phones and first generation iPads. However, nowadays this becomes less and less an issue and the mobile side of qooxdoo is evolving rapidly to provide a lighter weight solution. Basically, it keeps getting better and better.

Finally, here is a link to a discussion amongst qooxdoo developers about creating an IDE.
http://qooxdoo.678.n2.nabble.com/qooxdoo-quot-IDE-quot-Request-for-Comments-td3782909.html

From experience I think manual (text editing) form design is tedious and error prone and a tool to make it easier would be a godsend. qooxdoo's structure and "extends" capability would make it a prime candidate for a IDE implementation like Visual Studio uses with WinForms and .NET.

Is EXT JS a good alternative to JQuery

There are two parts to the Ext framework. Ext Core was invented as a jQuery competitor but honestly if you're trying to do what jQuery does, just use jQuery. It's more popular, it'll be easier to find answers, etc.

ExtJS is a full-blown RIA framework with a rich library of widgets. You might say that it competes with jQuery UI but jQuery UI is a much less rich set of components so they're not really competitors as such.

Also, ExtJS is released under either the GPL or a commercial license. You may find that to be a problem.

For rich Javascript frameworks, I tend to favour YUI or possibly SmartClient.

Raudus vs ExtPascal: Delphi web developement alternatives that use ExtJS

After using Raudus for a few months I decided to post my own answer.

The framework is improving, Sencha touch support now it is not complete but sufficient to create usable web applications optimized for mobile devices.

RFE, a new front end, not based on Sencha Touch is under developement and in next Raudus release (that should be out soon) there will be a usable preview of the new controls set.

So while ExtPascal seems frozen, Raudus is in progress and promising.

Update: I stopped using Raudus, it dropped ExtJs support and now it ships with own controls, that will never match the beauty and richness of extjs components. I am now going for IW + cgdevtools components that are Jquery UI for IW.

Best Framework for javascript /UI EXTJS vs HTML 5 vs other frameworks

Nothing beats pure Javascript. However there are a few good frameworks out there that will help you write good, manageable code.

Dojo - http://dojotoolkit.org/ It seems to be a robust framework for building large scale apps. Has all the fancy things to help you manage your codebase and a UI framework.

Requirejs - Just a good way to separate your code into reusable modules and load them as required. Helps in managing your code.

Backbone.js - A good library to manage your javascript data. Client side MVC-ish style of framework. Has the ability to sync with your server. Very extensible.

Underscore.js - A good library to manipulate javascript data. Has all of the fancy functions.

Jquery - A good dom manipulation library with a good ajax library and a few other nifty things. Great and popular library with many plugins and a simple plugin system.

Jquery UI - Works great with Jquery, lots of widgets.

Now it really depends on what sort of a client you have. If you need IE6 support, use Dojo UI library or Jquery UI. If you only need to support chrome & firefox & latest version of IE, you are usually better off with writing your own widgets (tabs, popups etc are all actually very simple widgets that can be implemented in 20 lines of code).