QuickCRC is a tool for responsibility driven design of object-oriented software using CRC cards. CRC cards are used to discover and document classes, responsibilities, attributes and collaborations between classes. Design scenarios can be identified and simulated. Complex designs can be partitioned into multiple diagrams with easy navigation through a contents view. The inheritance graph automatically shows the class structure of the evolving design. The user can assign the attribute access of each card responsibility and the tool presents an attribute access graph.