It's getting to the point where there are so many cool open source projects that I can't keep up. When you add in the currently battle royale of JavaScript projects that are basically just hip sounding words with ".js" added to the end, it's a little overwhelming. Seriously, just pick a word out of the dictionary at random and that's the name of an up and coming JavaScript library.

JavaScript MVC Frameworks and Libraries

This is an area that is very interesting but also very not-yet-baked. In the DOM manipulation and CSS selector space, jQuery won. That fight is over. The next big question is client side MVC frameworks. It seems everyone wants to make the next "Rails" framework on JavaScript and while there are some contenders, there's still lots of room for someone to "win."

DOM manipulation libraries like jQuery are important, but it's clear that making large and rich web applications requires more than just jQuery. More and more applications want smart asynchrony and dynamic loading.

(Reminder: All this IS overwhelming. That doesn't mean you need to know all these frameworks or feel bad that you don't know them all. Just accept that you DON'T know them all. Be OK with that.)

Here's the major players and ones you might want to be familiar with. Remember, these are client side libraries and while they often mention server-side frameworks like node or rails, these are things written in JavaScript that anyone can use.

Ember.js - Attempts to remove tedious boilerplate code. Includes a templating engine (no one will agree on just one), encourages an architecture where the browser does most of the work, supports state-management out of the box. Focus on computed properties, and templates that update themselves.

Underscore .js - A library of more than 60 functions to make JavaScript more fun and easier to use. Provides a layer that will use a modern browser's native implementation of a method while still supporting older browsers. Has iterators like each, map, reduce, etc. In a way, it's like LINQ for JavaScript.

JavaScriptMVC - A jQuery-friendly framework that adds functional testing, MVC plugins, documentation generation, dependancy management and build tools.

Spine.js - Seems like less than a Backbone (these libraries all play with each other's names). Introduces models and controllers, but for views, requires you use your own template engine. Intends to be super lightweight.

Backbone.js - Everyone loves Backbone. It's the one you'll hear about the most. There's a large community supporting it. Folks have said that large applications can get a little hairy and difficult to manage, though. Lots of great docs and examples.

Knockout.js - MVVM on the client rather than MVC. Lots of interesting client-side data-bind expressions. Rich documentation. And, wait for it, Knockback.js, a library that bridges the gaps between Knockout and Backbone and encourages you to use both effectively.

Sammy.js - A very small core library that brings in other adapters and plugins to give you just the parts you need. Focused on developer happiness. Works well with apps that are sitting on top of RESTful JSON server sides.

Angular.js - Includes templates, two-way data-binding and MVC, again, all on the client. Very small and starting to make a splash.

SproutCore - SproutCore seems to be very complete and more prescriptive than other frameworks. It also has a focus on making apps on tablets and other devices. The NPR for Chrome app used them.

Cappuccino - If you like and think in Objective-C, you'll like Cappuccino and Objective-J. Cappuccino is kinda of Cocoa (Mac APIs) for the web.

Google Closure - Almost doesn't belong in the list as it's a very complete toolkit with a whole worldview, rich library, templates, and lots of extras. You can choose how much you want to embrace, though.

ExtJS4 - This is a Sencha product and now on its fourth major release. It includes not only a framework and architecture but also widgets and charts.

PureMVC - Another MVC on the client side implementation, but this one was ported from ActionScript. It was originally used on Adobe Air and the like.

Batman.js - Bonus points for the best name. Explicitly embraces CoffeeScript as well as JavaScript. Only 2000 lines and very few extras. Very Rails friendly, prescriptive without being oppressive.

Require.js - A JavaScript file and module loader.

PrefixFree.js - A nice library that expands all your CSS to use the explosion of vendor prefixes correctly.

Lawnchair.js - Client-side storage and persistence. Less than a couch, but smaller and outside.

Mustache - Templates for views, explicitly without logic.

Handlebars.js - An superset of the Mustache template concept with extra features. A fancier mustache. Ahem, "Handlebar Mustache."

Also checkout Gordon Hempton's excellent "consumer reports" table on his blog that covers which JavaScript frameworks support which features.

ASP.NET Libraries, Frameworks and Open Source Projects

You may have heard that ASP.NET MVC 4, ASP.NET Web API and ASP.NET Web Pages v2 (Razor) are all now open source with contributions. They are up on CodePlex using Git. I thought I'd mention some interesting ASP.NET/CLR server side libraries here also as that's the area I work in. There are thousands of Open Source projects in the .NET space, but I wanted to take a moment and feature these as they are all related and all emerging.

Just like the JavaScript projects above, these .NET projects are all trying to innovate...trying to make something new and modern and compelling without sacrificing the good things about the past.

OWIN - This is the "open web interface for .net." It represents the "spec" of the web app function signature. It serves the same purpose as Rack spec on Ruby or WSGI on Python. "The goal of the OWIN interface is to decouple server and application, encourage the development of simple modules for .NET web development, and, by being an open standard, stimulate the open source ecosystem of .NET web development tools."

Gate - An OWIN Reference implementation of utilities, host handlers, and web framework adapters for OWIN. This is essentially glue code, with things like Gate.Hosts.Kayak.dll on one hand, and Gate.Adapters.Nancy.dll on the other, to fit together your stack, e.g. "Kayak->Owin->Nancy"

Nancy - A "Sinatra" inspired framework. "Nancy is a lightweight, low-ceremony, framework for building HTTP based services on .Net and Mono. The goal of the framework is to stay out of the way as much as possible and provide a super-duper-happy-path to all interactions."

Kayak - A 100% C# HTTP Server assembly that can be embedded in your project. "Kayak is an asynchronous HTTP server written in C#. It has been designed to be easy to embed into a variety of applications. Kayak natively supports the OWIN 1.0 Draft specification."

Firefly - Another 100% C# HTTP server assembly.

Manos - A 100% C# HTTP server in an assembly that is a part of a larger Manos web server + web framework bundle.

(web frameworks with owin adapters:)

(web frameworks with owin adapters:) AspNetWebApi - A framework optimized for HTTP APIs and services. Part of the open source ASP.NET Web Stack.

SignalR - A socket.io-like message bus that supports realtime communication over Web Sockets, long polling, forever frame, or server sent events. JavaScript and Server-side components.

Fubu - A MVC-inspired framework with the beginnings of some OWIN support.

OpenRasta - A development framework for building web-based applications and services. Focused on being RESTful.

There is no question that I've missed some. Leave them in the comments and I'll keep this post updated. Projects for this list should be of some renown and be pushing the envelope in some notable way.

Big thanks to Louis DeJardin for his help and bootstrapping the list.