Modeling and Verifying Information Systems with I-MAKS Information systems that process confidential data require special care to ensure that they don't leak confidential information. I-MAKS is a tool that supports the certification of information-flow security based on the Modular Assembly Kit for Security in the automated theorem prover Isabelle/HOL. Security certification with I-MAKS happens at the level of event-based specifications such that it is applicable to many settings, e.g. to software design, communication protocols, and distributed systems. In this talk, we will give an overview of I-MAKS and its features. Moreover, we will have a closer look into the application of I-MAKS to certify a confidentiality requirement on a communication platform.