The aim of internet traffic anonymization is hiding the origin of a request, for example it can be implemented by modifying the traffic trace ensuring the suppression of unwanted information. It is usually used for both privacy and security reasons. Its usage for preventing data mining is becoming more and popular in the recent years because of various reasons, for example implementing stricter laws and strengthening tracking activities. Different methods, tools and techniques have been developed for the purposes of anonymization. This study focuses on notorious anonymous communication systems and their comparison. We observe, evaluate and compare their capabilities such as scalability, unobservability, protection against security attacks, censorship-resistance, level of anonymity provided and others more precisely in the present research.