PromptBase is a marketplace that allows users to buy and sell high-quality prompts for AI models like DALL·E, Midjourney, ChatGPT, Stable Diffusion, and GPT. The platform aims to help users find the best prompts to improve their AI results and save money on API costs. It provides a wide range of prompt categories, including animals, art, cartoons, fashion, food, and more. Users can also earn money by selling their own crafted prompts on PromptBase. Additionally, PromptBase offers the ability to generate images directly within the platform using Stable Diffusion, and users receive five free generation credits every day. Overall, PromptBase serves as a platform for prompt engineering, enabling users to enhance the performance of AI models and monetize their skills.