In the last 10 years Open Source products have been widely used in industry. New methodologies and best practices to develop Open Source software appeared. In this work, we present an application that runs on Android-based mobile phones and collects proximity data with other devices via Bluetooth. The application gives new insights into measuring proximity inside a team of software developers. Data collection process is automatic so that the team members are not distracted from their daily activities. The collected data represent time frames when developers work alone at their machines and when they do Pair Programming with their colleagues.