Prompt Builder is a prompt engineering workspace for writing, testing, and saving prompts. Describe the task in plain English, and it helps you create a prompt that matches the model you choose. Start with a draft, refine it in chat, save or pin versions, then run them when you are ready. It works with GPT, Claude, Gemini, Llama, Mistral, DeepSeek, Grok, Perplexity, and more. You also get an Optimizer, an assistant for quick tests, and a library of reusable prompts and templates from the community. Turn an idea into a ready-to-use prompt in seconds. Refine it in chat, save it to your Library, and run it anytime.