This is Datawrapper Core, the open source platform that powers the charting tools hosted as free service on datawrapper.de.
Most of the functionality in Datawrapper is provided by plugins, some of which are open source but the majority is not. However, you are free to create your own visualization plugins.
Datawrapper was created by Mirko Lorenz, Nicolas Kayser-Bril and Gregor Aisch and has in the past received funding by ABZV.
To get in contact to us, please reach out via Twitter at @datawrapper or send an email to firstname.lastname@example.org. Unfortunately, we're not able to respond to Github issues.