ProjectHuddle - Get design feedback and client approval using WordPress.
React Proto - React application design and prototyping tool
Savahapp - The all-in-one design sharing, collaboration, workflow and app prototyping platform
UI Bakery - An intuitive visual internal tool builder. Allows you to create admin panels, CRMs, customer support tools on top of your database. Integration with MySQL, PostgreSQL, MongoDB, and more. Add business logic, manage user permissions, share your app.
Specfox - A free platform for creating beautiful website and mobile app specification documents for your team. No more word templates!
Invision - Prototyping and collaboration for design teams