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While not new to the world, the GTK+ based diagram creation program called Dia will be new to many people.

In corporations, Microsoft’s Visio application is regalling many. This produces terrific network diagrams, business flow charts, mindmaps and all sorts of other diagrams which can be reduced to the interconnection of graphical blocks. As a presentation tool it’s up there with PowerPoint.

However, Visio costs – which makes sense; it’s a commercial app. But even those who shell out for the full Office 2007 Professional only get a Visio viewer bundled; you have to pay more for the Visio content creator itself.

By contrast, Dia – which openly admits to being inspired by Visio – is free to use, free to modify and free to distribute. Further, as well as Windows, it runs under Linux. Although the latest version is still presented as sub version 1 – namely 0.96.1 – this is a mature and stable product.

Dia’s built-in shape libraries are mostly technology oriented, with E-R and UML diagrams, flowcharts, network hierarchies and related object collections. Additional digital logic and CMOS shapes are also available elsewhere. Although the standard library is less-replete than Visio, this is not a significant burden for two reasons.

Firstly, the package has a well-defined method for importing new shapes, which are defined as XML files using a subset of SVG (a standard for scalable vector graphics), and secondly, the latest version can import VDX files from Visio. (The default Visio file format is .vsd, however Visio allows diagrams to be saved as XML, which creates .vdx files.) All this means that additional shape collections are easily created with a bit of creativity and in time I’d expect to see a larger library available as people submit their own contributions.

Downloads and documentation are all available on a Wiki site which includes the developer’s envisioned roadmap toward version 1.0.