A developer kit can be downloaded for free as either GUI installer or a headless version (delivered as a tarball). The product is dual-licensed under a commercial license and the "1060 Public License," summarized on the web site in short form:
NetKernel is licensed under the 1060 Public License - which like the GPL is viral for distribution of modifications to the Kernel and system components.From first looks, NetKernel is more of a business integration tool (like an ESB) than an application server, although it's quite possible (and likely) that it has features Your Humble Editor hasn't seen yet. It's certainly easy to use and the tutorial (hosted from in the application itself) is quite good (again, at first glance only - I haven't stretched the system by any means.)
For *use* of the system it mandates OSI licensing, a quick summary is: NetKernel is on the open-source commons, if you use it on the commons (ie open-source your application code) it's free, if you want to take it off the commons (ie keep your source closed) then you must pay. Unlike GPL we let you choose which OSI license you like best if you choose to open-source your application code.
Hopefully our license represents a business model that's fair to the open source community, fair value to the commercial world and means we get to feed those hungry kids...