Stranger Meetup, I Can Haz Chat and ChattUSA are free chat sites that don't require registration as of April 2015. These sites are available for anyone to use without an account, but some features on certain sites may require a higher level account, such as registration or authentication.
Stranger Meetup pairs people with other users randomly to chat. The chats are entirely anonymous and use no pictures, personal information, video or audio to help with the chat. Instead, each chat is entirely text-based. The site provides flirting tips to users interested in dating online, and it maintains a page with information about common chat acronyms and abbreviations.
I Can Haz Chat allows users to create accounts if desired, which comes with certain privileges, such as the ability to save preferences and create a site profile. The site also has a paid account option. However, users can chat via text, video and audio for free without registering. Users can join pre-existing chat rooms or create their own.
ChattUSA requires some basic information, such as a nickname, gender and age, but it doesn't require a formal registration. The chat system requires no downloads and is a text-based system with no video or audio options. Users must be at least 16 to use the service.