We present CognitIDE, a tool for collecting physiological measurements, mapping them to source code, and visualizing them directly within IntelliJ-based Integrated Development Environments (IDE)s. CognitIDE facilitates the setup and conduction of empirical studies evaluating the relationships between software artifacts and physiological parameters. Corresponding measurements enable researchers to evaluate, for example, the cognitive load software developers are experiencing. Our tool lets study participants use IDEs in a natural way while eye gaze, further body sensor data, and interactions with the IDE are collected. The recorded data can be used for studying aspects such as code comprehensibility. Furthermore, CognitIDE enables highlighting code positions according to the physiological values collected while corresponding positions were looked at. The possibility of visualizing physiological measurements and inferable variables, such as cognitive load in the code, facilitates the identification of poorly maintainable code and provides a direct way of letting study participants reflect on whether the measurements mirror their perception. Moreover, the plugin has additional features for facilitating studies, such as interrupting participants and letting them answer predefined questions. Our tool supports the recording of measurements with the wide variety of devices supported by the Lab Streaming Layer. Thanks to its versatility, CognitIDE can be easily adapted to the requirements of different studies.