Coffer is a Chrome extension that adds a save button to ChatGPT, Claude, and Gemini responses so you can capture and store useful AI outputs locally as formatted Markdown in a single, searchable vault; it preserves headings, lists, and code blocks, unifies outputs across multiple AI assistants, and keeps data on your device for privacy, making it easy for knowledge workers, developers, students, and creators to reuse and find high‑value AI answers instead of losing them in chat history.