MockFlow is an online tool to create and share user interface designs for software & websites.
This desktop client provides all the features of its web counterpart that includes real-time collaboration, team chat, sitemaps, export, feedback collection, revisions…
Plus it adds offline capabilities and caching.
All your UI designs are automatically stored locally. So you can edit and view mockups even with No net-connectivity. And optionally sync back when you regain connection.’