Passwords pasted into chat live forever, but a Cryptgeon note vanishes the moment it has been read. You type a note or pick a file, press create, and get a share link with a QR code to hand over. Encryption happens in the browser with XChaCha20-Poly1305, so the server holds only ciphertext and never sees the key that sits after the hash in the link. Advanced options set the number of views or a lifetime in minutes, and a custom password can be required on top of the generated key. Everything is kept in memory in a Valkey or Redis cache, so nothing is written to disk. Operators tune limits with environment variables for note size, maximum views, maximum expiration, file uploads, and ID length. The interface is a calm monospace page with dark and light themes. A command-line client sends notes from a terminal, and a Raycast extension covers the macOS launcher. Theme text, logo, favicon, and an imprint page can be customized to match a team or company. A health endpoint reports status to proxies and orchestrators. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. MIT licensed.