The Declared Type Generalization Checker is a plug-in for Eclipse’s Java Development Tools (JDT) that supports developers in systematically finding and using better fitting types in their programs. A type A is considered to fit better than a type B for a declaration element (variable) d if A is more general than B, that is, if A provides fewer members unneeded for the use of d. Our support comes in the form of warnings generated in the Problem View of Eclipse, and associated Quick Fixes allowing elements to be re-declared automatically. Due to the use of Eclipse extension points, the algorithm used to compute more general types is easily exchangeable. Currently our tool can use two publicly available algorithms, one considering only supertypes already present in a project, and one computing new, perfectly fitting types. 1 The Problem: Too Strong Coupling Due to Overly Specific Types A class C is coupled to a type B if one or more declaration elements of C (i.e., fields, formal parame...