The CDK classes are Java utitility classes for ChemoInformatics and Computational chemistry, written in Java. They are developed constantly developed parallel to other projects that make use of them. They are a complete re-write of the CompChem classes that were the basis of JChemPaint, a Java Editor for 2D chemical structures, and of JMDraw, a Java package for the graphical layout of 2D chemical structures.

The Chemistry Development Kit (CDK) was founded on 27 September 2000, when Christoph Steinbeck (from JChemPaint) and Egon Willighagen (CML patches) visited Dan Gezelter (from Jmol) at Notre Dame University in South Bend near Chicago. The three had a brainstorm session on the general design of the core data classes, for which the skeleton was then implemented by Chris on his flight home to Germany. Today, almost five years later, the CDK has evolved into an international 30-member open source chemoinformatics project with growing public awareness.