Easel.io has been acquired by GitHub, announced today on Easel’s company blog.  From YC S12, Easel is an in-browser web design tool.  The company’s service will continue post-acquisition, providing support and additional benefits to paid subscribers.

Better workflow for designing the web is Easel’s core goal.  For designers, there’s modern technologies like web fonts and CSS3.  Product managers benefit from faster prototyping and testing.  Developers can use Easel for quickly coding site structure and presentation.  Easel’s Chrome extension makes it easy to import existing HTML/CSS.  Native support for Twitter’s Bootstrap framework is also useful and innovative.

Co-founder Matt Colyer previously founded Flagr, from Y Combinator’s second batch in Winter 2006.  Mr. Colyer subsequently worked at AdRoll as an engineer with Easel co-founder Ben Ogle.  Acquiring company GitHub is a popular platform for software project collaboration, code review, and code management.