Published Article / Planning problems are frequently encountered in everyday situations. The brute force approach of evaluating every possible solution for any medium size planning problem is just not feasible. Drools Planner is an open source Java library developed to help solve planning problems by using meta-heuristic algorithms. Drools Planner uses the Drools Expert (rule engine) for score calculation to greatly reduce the complexity and effort required to write scalable constraints in a declarative manner. This paper presents an introduction to Drools Planner, how it can be used to solve problems and concludes with an example scenario.