I used Gridbox for a day to see if I can speed up the development of an app I'm building.

Pros:

Easy to create HTML pages you can export. Great pricing structure!

Cons:

Haven't found any so far.

Hello Everyone, We’re excited to launch Gridbox Public Beta - Simplest Visual Interface Builder for Bootstrap and Foundation. Say, hello to a whole new way to design prototype for the web. Gridbox combines the speed of drag and drop tool and the beauty of hand-coded HTML and CSS. We built Gridbox as a tool to help professional front-end developers and designers kickstart their front-end projects faster and spend less time on wireframes and mockups. Whether you’re working with a client at the beginning stages of a new application, or just need to a build simple web prototype for your project, we want to help. Here are a few features, we’re most excited to launch with 1.0: 1) Drag and Drop Bootstrap/Foundation Components Drag and drop ready-to-use bootstrap and foundation components. Create your web page in seconds by adding the components you need. 2) Full-Document HTML Editing Gridbox allows for full document source editing, allowing you to add external stylesheets, webfonts, scripts, and more. 3) Preview Modes and Export While you’re working, you can get real-time preview of your changes or you can toggle on a preview mode with one click to see how things are shaping up. Yet another advantage you’ve with Gridbox is you can also download the entire project as a .zip file. And this is just the beginning. We know we have a long way to go, so I’m looking forward to your feedback and questions.

Mail confirmation isn't working and unsafe. But yeah, really good tool! :)