Overture is a powerful basis for building really slick web applications, with performance at, or surpassing, native apps. It's a library of most of the general-purpose frontend code that powers FastMail.
To get a feel for what an Overture App looks like, check out our classic Todo demo app. You can also see the performance compared to other popular frameworks in this demo.
If you want to delve deeper, there's fairly complete API documentation; we'll fill in the gaps over time.
To grab the code, either download a pre-built version of Overture, or clone our repository on GitHub.