Lucidchart
Online diagram and flowchart software that supports Microsoft Visio import and can work on any operating system.
Wireframe your Ideas iPlotz allows you to rapidly create clickable, navigable mockups and wireframes for prototyping websites and software applications. Create a...
Wireframe your IdeasiPlotz allows you to rapidly create clickable, navigable mockups and wireframes for prototyping websites and software applications.Create a project, add wireframe pages with design components and discuss your creations with others.
mockups wireframes wireframe-prototype design
Online diagram and flowchart software that supports Microsoft Visio import and can work on any operating system.
Freemium
Pencil is a standalone app or Firefox extension that lets you create diagrams or UI mockups. It doesn't have collaboration/multi-user features.
Free Open Source Mac OS X Windows Linux Firefox Electron / Atom Shell
OmniGraffle can help you make eye-popping graphic documents—quickly—by providing powerful styling tools, keeping lines connected to shapes even when they’re moved, and magically organizing diagrams with just one click.
Commercial Mac OS X iPad
Using Balsamiq Mockups feels like you are drawing, but its digital, so you can tweak and rearrange controls easily, and the end result is much cleaner.
Commercial Mac OS X Windows Web
ConceptDraw PRO v11 is the only product that supports Visio legacy, runs on macOS and Windows, and is a perpetual license. Import/Export VDX, VSDX, VSSX and Import VSD, VSS files.
Commercial
Free web and mobile mockup tool. Transform your design and mockups into clickable interactive applications. Perfect way to validate ideas faster with lean startup thinking. Best tool for quick prototyping.
Freemium Web
mockingbird is an online tool that makes it easy for you to create, link together, preview, and share mockups of your website or application. It is not Flash based.
Commercial Web
Simple vector graphics editor for creating flowcharts, UML class diagrams, illustrations and slide shows.
Free Windows