Every designer and developer build their own good and reliable wireframe. The importance of wireframe is the difference between designers, some prefer to use them and others don’t. Personally, I use wireframe in most of my projects, it gives be a better idea of what is where and why. If you enjoy building unique designs from scratch then you will certainly enjoy using wireframe builders, so here are some free and popular wireframes most of us use.
Pencil in an opensource sketching tools. This tools can greatly help your business analysts and GUI developers to quickly draw GUI of applications to prepare proposal documents for clients to collect requirements.
mockingbird is an online tool that makes it easy for you to create and share mockups of your applications and websites.
Design, collaborate user interface concepts for your software and websites.
fluidIA is an agile design tool for prototyping rich user interfaces. UX professionals and developers can create your own prototyping tool in an open way.
This tool helps you create your own iPhone mockup in illustration or pencil style.
Quick mockup creation and prototyping tool.
Cacoo is a user friendly online drawing tool that allows you to create a variety of diagrams such as site maps, wire frames, UML and network charts. Cacoo can be used free of charge.