Pencil is a free and opensource tool for making diagrams and GUI prototyping that everyone can use. Top features: * Built-in stencils for diagraming and prototyping * Multi-page document with background page * On-screen text editing with rich-text supports * PNG rasterizing * Undo/redo supports * Installing user-defined stencils * Standard drawing operations: aligning, z-ordering, scaling, rotating... * Cross-platforms * Adding external objects * And much more... WWW: http://www.evolus.vn/Pencil/