Visual Studio Express 2012 for Web, or VS Express for Web as its shortcut is called, is a fairly competent free IDE for developing Browser apps. It has some nice entry-level features, that compete favorably with features in IntelliJ IDEA Community Edition (Free) and WebStorm, both from JetBrains.
These are some noteworthy features
Open a Web Site from a folder. Execute it in Google Chrome. Yes, that is quite literally the default browser if you have it installed. Static content is delivered by an ASP.NET Development Server.
HTML editor does syntax highlighting, code folding, and document formatting. It validates HTML on the fly and shows errors in the editor. You can jump to CSS style definitions. It has a design mode, where you can do WYSIWYG editing, add typical HTML components (tags) from the toolbox, and edit their properties. Nice for typical server request/response applications, but not so useful for single page applications.
CSS editor does syntax highlighting, validation, and document formatting. IntelliSense supports CSS3. Context-sensitive help for a keyword (F1) takes you to its documentation at MSDN.
There are several things that can be improved. Refactoring support, a tremendous feature in WebStorm, would be a welcome addition. I haven’t yet had the opportunity to try other editions of Visual Studio 2012. Better features are probably reserved for the paid editions.