Whynot is a generic JavaScript-based language matching framework, built by a lead developer of Dutch web development company Liones. According to the developer's assumption, change of the underlying structure of the framework from Nondeterministic Finite Automata to Deterministic Finite Automata could be profitable for the performance of the framework. This thesis tests the assumption: it covers the theoretical topics of Finite Automata, Regular Languages and Algorithm Complexity. The theory is further used as a base for building a simplified version of Whynot with Deterministic Finite Automata as underlying structure and testing it against the original Whynot. The test results show that, under a certain assumption, the change of the unde...