Privacy Policy

Last updated October 24, 2026. Covers the DuoBook iPhone app and the DuoBook Host Mac app.

The short version: DuoBook collects no data. There’s no account, no analytics, no advertising, and no tracking. Your Mac’s screen, sound, and your typing go directly between your own iPhone and your own Mac, encrypted, and we can’t see any of it.

What stays on your devices

• Pairing keys. When you pair, your iPhone and Mac agree on a secret key. It’s kept in the iPhone’s Keychain and on your Mac, and it never leaves them.
• Your list of Macs and your settings (theme, key sounds, pointer speed, and similar) are stored on the iPhone.
• The iPhone’s name is shown on your Mac when you pair, so you know which device is asking.

What goes between your iPhone and your Mac

While you’re connected, the Mac sends its screen picture and, if you turn it on, its sound to the iPhone, and the iPhone sends your keystrokes, pointer movements, and gestures to the Mac. Everything is encrypted end to end with keys only your two devices have. If you choose to, the iPhone also sends:

• text you paste or type with the iPhone keyboard,
• photos and files you pick, which are saved in the Mac’s Downloads folder,
• and, if “Copy from Mac’s clipboard” is on, the Mac sends text you copy there to the iPhone’s clipboard.

DuoBook Host captures the Mac’s screen (Screen Recording permission) and types and clicks for you (Accessibility permission) only to do this, and only while your iPhone is connected.

Reaching your Mac away from home

• Your router. If you turn on “Access from anywhere”, DuoBook Host asks your home router (using the standard NAT-PMP or UPnP protocols) to forward one port to the Mac.
• Your iCloud. While remote access is on, DuoBook Host saves a small record in the private iCloud database of your Apple Account: your Mac’s name, its current internet address and port, a relay address if you set one, a random identifier for your Mac, and when it was updated. Your iPhone reads it to find the Mac. Private iCloud data is only accessible to you; we can’t read it. The record is deleted when there’s nothing to share (remote access off).
• Relays (optional). If you set up a relay server, it passes along the encrypted connection without being able to read it. Like any internet server, it sees the two devices’ internet addresses and a random identifier; the relay software that comes with DuoBook logs only when sessions start and end (with a shortened identifier) and the address of malformed requests. Whoever runs the relay controls those logs.

What we collect

Nothing. DuoBook has no servers that receive your data, contains no third-party analytics or advertising code, and doesn’t track you across apps or websites.

If you’ve chosen to share diagnostics with app developers in your iPhone’s or Mac’s settings, Apple may give us anonymous crash reports. You can turn that off in Settings → Privacy & Security → Analytics & Improvements.

Children

DuoBook isn’t directed at children and collects no personal information from anyone.

Deleting your data

Forget a Mac in the iPhone app (swipe left on it) to delete its pairing key from the iPhone; remove the iPhone in DuoBook Host to delete it from the Mac. Deleting the apps removes their settings. The iCloud record is removed when you turn off “Access from anywhere” (and any relay) in DuoBook Host, and you can also delete DuoBook’s iCloud data in System Settings → [your name] → iCloud.

Changes and contact

If this policy changes, we’ll update this page and the date above. Questions? Write to info@mehdichitsaz.com.