Several methods exist for protecting applications from attackers outside of secure coding practices. Most of these, however, require piling on extra layers of security in the form of web application firewalls (WAFs), web server modules, or complex middleware. In this talk we discuss a different approach: self-defending applications. Ensnare, a easy to install Ruby Gem, takes these concepts and moves them from the web server, middleware, and external devices into the application itself. This helps eliminate unnecessary hops and network latency while also increasing the intelligence that can be applied to the rulesets and responses. By residing in the application layer, Ensnare can take advantage of full knowledge of a user's actions and history in order to detect malicious behavior, and produce a much wider range of potential responses in order to block, confuse, or redirect the attacker. Ensnare is extensively customizable and allows the creation of traps and responses that are relevant to the specific application being protected. In this talk we will walkthrough the concept and design of the Ensnare framework. We will also show a demonstration that show exactly how Ensnare can be used and customized to provide a unique protection against web application security threats.