These are open source companion projects, for the Apache Isis open source project.
OSSRH-10641, you set up isisaddons.org as a catalog of companion projects. This domain/group of projects is similar, but relates to higher level business-oriented components.
Me and the other mentioned user are core committers of the Apache Isis project; Jeroen has registered the incode.org domain name (see whois.net). You'll see that we are both members of the "incodehq" organization on github (https://github.com/incodehq/)