Network and data commitments

Last updated: October 17, 2026

Nothing happens where you can't see it. Everything Casement does is written on this page.

In short

• Casement only talks between your computer and your devices. There are no relay servers and no accounts.
• No ads, analytics, tracking or telemetry.
• Casement Home on your computer never connects out to the internet on its own, not even to check for updates.

That does not mean "no network traffic at all". Casement itself announces your computer on the local network so devices can find it, and resolves names. App Store and OS checks, and Tailscale traffic, are handled by the operating system or by Tailscale. The lists on this page are complete.

Who Casement talks to

• Casement Home on your computer only answers connections made to it. It never connects to anyone else on its own.
• Casement on your device only connects to the computers you chose: picked from the list, entered by hand, or an address that computer gave it.
• Screen images, sound and input travel directly between your computer and your device. Away from home, they go through Tailscale.

Other traffic Casement itself sends

Casement Home shares Tailscale destinations as numeric IP addresses, without reverse DNS lookups.

These announcements are visible to others on the same network. They carry only the computer's name, ID and local network address. Tailscale addresses are shared only with devices that have already paired.

Traffic handled by the OS or Tailscale (Casement holds neither the destination nor the content)

• App Store: downloading, updating, purchasing and restoring purchases. The operating system talks to Apple.
• OS checks: when you open Casement Home, the operating system checks its notarization and developer certificate (Gatekeeper on a Mac).
• Crash reports: on a device running Casement (including a Mac), they reach the developer through Apple only if you have turned on "Share with App Developers" in the system settings. Casement Home is distributed outside the App Store, so its crash reports have no route to the developer. Casement never sends them itself.
• Tailscale: the route used when you connect from outside your home network is provided by Tailscale.
• Pages you open with a button: casement.win, or sharing the Casement Home download link. Casement just asks the operating system to open them.

What Casement never does

• Include ad, tracking, analytics or crash-collection SDKs
• Run its own servers (for relaying, accounts, licence or purchase checks, telemetry or update delivery)
• Let Casement Home download updates from the internet
• Save activity logs without you asking

Encryption and authentication

• Connections are encrypted with DTLS 1.2 or later, directly between your computer and your device. Older versions are refused.
• Encryption keys are made anew for every connection. Sessions from earlier connections are never resumed.
• The first time you connect, your device and your computer show the same 6-digit number. Only devices you allow on the computer can connect.
• After that, every connection is checked with keys unique to each device and each computer.
• You can remove a pairing in Casement Home's settings. Removing it disconnects that device immediately, even mid-session.
• Casement Home on your computer creates its own certificate, without relying on a certificate authority or a cloud service. Your device remembers the key of the computer it first verified and refuses any other key.
• The device's keys stay on that device. They are not synced to iCloud or included in backups.
• The computer's key is kept in the operating system's key store (the keychain on a Mac), in a part that only Casement and Casement Home can read. Other apps can't see it. It is not synced to iCloud or any other service and doesn't move to another computer.

Data

• Screen images, sound and input are not stored, with one exception: the background of a Home Screen widget. Only for apps whose widget has "Desktop window in background" turned on, Casement keeps one small, heavily blurred image (360×360) of the window you last viewed, one per app, on your device. The unblurred image is never written to a file. Remove the widget or turn the setting off, and the image is deleted the next time you open Casement.
• When Casement moves to the background, iOS and iPadOS keep a picture of the screen on your device for the app switcher. This is done by the operating system, and Casement does not use it.
• By default, Casement Home does not save activity logs, because logs would contain window titles and app names.
• Clipboard: when sharing is on, copied text is sent between your computer and your device. Text is sent when you copy on your computer (computer → device), and right before you paste on your computer text you copied on your device (⌘V on a Mac; device → computer). Images and files are not sent. Turning off "Share Clipboard" in Casement's settings on your device stops it.
• Casement never sends anything to be stored outside your computer and your devices.

Updates

• Casement on your devices is updated through the App Store.
• Casement Home never fetches updates itself. When a newer version of Casement connects to it, the computer shows "A new Casement Home is available". You download it in your browser from casement.win, and the operating system checks that the file is genuine (Gatekeeper and notarization on a Mac).

How you can check

An automated check counts every call to the networking APIs it knows about. If one is added or removed, the build check fails. The check only sees how many calls there are, so we also read the code to confirm the destinations and the components we use whenever it changes. The lists on this page are what both of these confirm.

You can also check for yourself with a network monitor such as Little Snitch or LuLu.

Reporting a vulnerability

If you find a security issue, please write to [email protected] (security.txt).