AutoResponder is a tool that allows users to send automatic replies to their favorite messengers, such as WhatsApp, Facebook Messenger, Instagram, Telegram, Signal, and Viber. It features unlimited messages, the ability to connect to web servers, ChatGPT/GPT-4 or Dialogflow AI, and the ability to trigger custom actions. It has been downloaded over 4 million times, and users have noted its ease of use, customizability, and reliable performance.