The Karel Appel Foundation is the custodian of the Karel Appel Archive in its entirety.

The archive comprises the documentation of the works and the life of Karel Appel, including information about his oeuvre, his poetry, other writings and correspondence. It is continuously supplemented by new documents and other information concerning his work.

It forms the center of knowledge for scientific research and is the basis for publications of the oeuvre of Karel Appel. 

Requests for information must be submitted in writing to the Karel Appel Foundation along with a detailed description of the purpose of the research.