In many domains, such as bioinformatics, cheminformatics, health informatics and social networks, data can be represented naturally as labeled graphs. To address the increasing needs in discovering interesting associations between entities in such data graphs, especially under complicated keyword-based and structural constraints, we introduce Conkar (Constrained Keyword-based Association DiscoveRy) System. Conkar is the first system for discovering constrained acyclic paths (CAP) in graph data under keyword-based constraints, with the highlight being the set of quantitative constraint metrics that we proposed, including coverage and relevance. We will demonstrate the key features of Conkar: powerful and userfriendly query specification, efficient query evaluation, flexible and on-demand result ranking, visual result display, as well as an insight tour on our novel CAP query evaluation algorithms. Categories and Subject Descriptors H.3.3 [Information Systems]: Information Storage a...