Here you can find various resources like documentation and software packages.
The WebODF community website.
The WebODF source repository.
WebODF white-paper with information about the WebODF technology and how to deploy it. You can download the latest version from here.
The ViewerJS community website.
The ViewerJS source repository.
The Krita community website
The Krita source repository
The Calligra community website.
The Calligra source repository
Calligra White Paper
This white paper describes the contents and technology of the Calligra suite. You can download the latest version from here.
The OpenDocument Specification.
The OpenDocument Technical Committee where KO GmbH takes part.
OpenDocument on Wikipedia -- The OpenDocument format