Jay Freeman (@saurik) is the primary developer and community manager of Cydia, a platform for distribution and development of extensions to third-party applications on iOS. Substrate, which is also available on Android, acts as the core of Cydia, providing a library and framework that makes it easy for developers to perform modifications to third-party applications. He also develops Cycript, a popular tool for manipulating and exploring applications on iOS and Mac OS X at runtime using a highly-interactive JavaScript console. On the side, Jay teaches Computer Science at the College of Creative Studies, University of California, Santa Barbara.