TweetGPT is a Chrome browser extension that uses the OpenAI API to generate tweets and replies. With the TweetGPT extension, when you open a new tab on Twitter, you will see a robot icon under the tweet section. By clicking on the icon, a new tweet will be generated with a random tweet type, such as positive, negative, controversial, etc. Additionally, for a reply, the extension will generate a tweet based on the original tweet and for a new tweet, it will write a tweet based on the current trending topic.