What is OpenJUMP

"JUMP is a computer program that uses a unified mapping platform as a visualisation framework..." (changed ESRI keynote on What is GIS? by M. Bobzien)

But to be a bit more serious - OpenJUMP is an open source GIS software written in Java and it is based on JUMP GIS by Vivid Solutions. Furthermore...

• It is a Vector GIS that can read rasters as well
• OpenJUMP is known to work on Windows, Linux and Mac platforms, but should work on any operating system that runs Java 1.5 or later.
• It is not just another free demo viewer, but you can edit, save, analyze etc. with JUMP / OpenJUMP
• It works, even with medium size datasets, and with professional touch
• It provides a GIS API with a flexible plugin structure, so that new features are relatively easy to develope around the sound mapping platform.
• It utilizes OGC standards like SFS, GML, WMS and WFS
• It is already translated in English, Finnish, French, German, Italian, Portugese and Spanish. The translation in other languages is in progress.
• ..and it is free (under the GPL license).

OpenJUMP finally adds some key enhancements to the original JUMP software, including:

• I18N (internationalization),
• more drawing and geometry editing tools,
• advanced attribute query,
• enhanced set of selection tools,
• image export in Scalable Vector Graphics (SVG) format,
• option to show the actual map scale,
• function to copy objects including attributes,
• a tool to zoom to a user defined map scale,
• it can show layers dependent on the current map scale,
• preparation for Mr SID raster files
• ...

more detailed info:

• Screenshots
• OpenJUMP Features
• OpenJUMP Supported Data Formats
• OpenJUMP History
• OpenJUMPs Family