Maqetta is an open source project that provides WYSIWYG visual authoring of HTML5 user interfaces. The Maqetta application itself is authored in HTML, and therefore runs in the browser without requiring additional plugins or downloads.
Maqetta allows user interface designers (sometimes known as User Experience Designers – UXD) to perform drag/drop assembly of live UI mockups. One of Maqetta’s key design goals is to create developer-ready UI mockups that promote efficient hand-off from designers to developers. The user interfaces created by Maqetta are real-life web applications that can be handed off to developers, who can then transform the application incrementally from UI mockup into final shipping application.
For team development, Maqetta includes a web-based review&commenting features with forum-style comments and on-canvas annotations.
Maqetta is available under a commercial-friendly open source license. You can download the source code and install it on your own server, customize the code to fit your needs and/or contribute improvements to the open source project.