Shapes is a simple, elegant Graphing and Diagramming app. Shapes gives you all of the most important features you need in a Diagramming tool without all the extra cruft, at an affordable price. Shapes has support for "connected" lines. When resizing lines, the lines magnetically snap to other shapes. Then, as you drag the connected shape around the canvas, the connected lines adjust themselves as well.
Shapes is great for Programmers and Web Designers looking for a simple tool for rapidly designing Flowcharts, laying out Wireframes, or visualizing Model Relationships.

Shapes lets you get to work quickly by giving you just the basic tools you need in a slick, single-window user interface. Shapes is a thoroughly Mac-native app offering QuickLook support, Fullscreen Mode, Version Browsing and iCloud Document Storage.

Important note on Shapes 4 and compatibility:
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Shapes 4 is not a free upgrade from prior versions of Shapes. Shapes has always been very inexpensive, and up to this point I've offered many, many new features via free updates. With Shapes 4, it's unfortunately time to finally break that cycle. Shapes 4 is $9.99.

Shapes 4 will not support the old .shapes file format from earlier versions of Shapes. You won't be able to edit or open files created in earlier versions of Shapes using Shapes 4.

Shapes 4 supports a new file format, called .shapesdoc which is not supported by earlier versions of Shapes. The new file format handles embedded images far more efficiently than the old format.

Compatibility: OS X 10.8 or later, 64-bit processor