Replika was created by Eugenia Kuyda to remember and honor her closest friend, Roman Mazurenko. It began as a simple AI chatbot that would respond like him using text messages fed into a neural network. The project has since evolved into an app that provides a safe space to discuss your thoughts, feelings, beliefs, experiences, memories and dreams—your “private perceptual world”. One way Replika works is through A/B testing natural language models to find the most engaging responses. CakeChat was their first open source model but they now use GPT-2 and GPT-3 for more sophisticated results.