It is only natural that open source vendors are among the first companies who provide the implementations of the Decision Model & Notation (DMN) standard. When the DMN 1.0 became publicly available for the very first time on September 26, 2013, it was an open source vendor, OpenRules, who just in a few weeks announced its first implementation of the DMN 1.0 Primer. And today, on July 23, 2015, a new open industry initiative was formed to promote the DMN standard “by providing an open source reference implementation for automatic execution of DMN models.” It currently includes: Signavio, Alfresco, Omny Link and Bruce Silver Associates – read the proper announcement here.
The complete current Catalog of DMN supporting tools can be found at http://openjvm.jvmhost.net/DMNtools/. You even may compare their DMN implementations feature-by-feature. If your product also supports (or plans to support) the DMN, you may add it to the Catalog from here.