MaskPaste is a local-first macOS app that masks sensitive text — names, companies, addresses — before you paste into ChatGPT, Claude, or any AI. Drag-select what to hide, pick a replacement, copy. When the AI replies, paste it back and your originals return. No accounts, no telemetry, nothing leaves your Mac. Built for anyone using AI in client work, healthcare, legal, or any context where pasting raw text feels risky.