BFF is an AI tool that acts as a supportive diary, engaging in conversation with users about their daily lives. It allows users to discuss various aspects such as career, goals, relationships, and emotions. The AI sends a text message to users every day, providing a unique way to reflect on and process their experiences. BFF differentiates itself from a traditional diary by actively responding and engaging in dialogue with the user. The tool is available for purchase in iMessage, with different options for pricing. Users can choose between a free version, which utilizes GPT-3.5 and allows for 5 messages per day, or a Pro version for $10 per month, which uses GPT-4 and enables unlimited messaging. BFF also has the ability to learn more about each user over time. This AI tool has the potential to serve as a personalized virtual companion, assisting with self-reflection and emotional support.