JavaScript Web Applications are being used by virtually all tech companies in the world today, from startups to Fortune 500 organizations. Increasing amounts of logic are being shipped to the browser because of this. There is a need to interact with critical data such as user credentials, personally identifiable information, credit card numbers, etc - in other words, very sensitive information. Because JavaScript is highly dynamic, it's very easy to interfere with the apps behavior and its execution environment, thus there are risks that need to be addressed. In this talk we will discuss what is the current state of the art regarding the integrity of Web Applications on the client-side, show some attack scenarios. and how to avoid them.