Img2Prompt is an AI tool that generates text prompts from images. It uses stable-diffus and clip-vit-l/14 models to create approximations of text prompts based on uploaded images. The tool has a public API and users can run the models on their own hardware or on a cloud platform such as Replicate with an Nvidia T4 GPU. The tool can be used for various applications such as creating captions for images or generating new images based on a given text prompt.