Bridge the Gap is a trend that aims to allow web browsers to start smartphone apps on a mobile device. This is achieved by so-called Deep Links, which enable direct linking to specific in-app resources. However, the resulting fusion of the web and native apps also introduces new attack vectors. There are numerous studies on security and privacy concerns of Deep Links on the open-source operating system Android, showing that these are prone to threats such as hijacking. The proprietary operating system iOS has a similar implementation of deep linking mechanisms to Android. However, there are not many publications on this matter, possibly due to the unavailability of iOS’ source code. In this thesis, we investigate the security of mobile Deep Links. First, we present known attack scenarios for Android with regards to Custom Schemes and App Links. Then, we consider the applicability of these attack vectors to deep linking mechanisms on iOS. Therefore, we develop vulnerable apps implementing discussed security issues, analyze whether an attacker could abuse them, and what security and privacy implications this has. Next, we compare our results to the corresponding mechanisms and security concerns of Android. Finally, to gain an insight into the actual security implications of the presented attack vectors, we analyze the distribution of Deep Links in the wild, based on a dataset containing over 11,000 iOS apps from the official Apple App Store.