Snapdown is a macOS utility that converts any selected region of your screen into structured Markdown, preserving headings, lists, tables, and reading order rather than producing flat OCR text. It runs entirely on-device on Apple silicon, requires no account, and processes everything locally so captures are never uploaded. Users can trigger a capture with a single keyboard shortcut and paste the resulting Markdown directly into documents, issue trackers, coding agents, or LLM prompts. An Aggregate Mode lets users combine multiple smaller captures into one structured document, reducing visual noise from large or complex screens.