Terms Of Use

Effective November 15, 2026. Applies to the DuoShell app for iPhone and iPad, the DuoShell Pair app for Mac, and this website.

These Terms of Use ("Terms") are an agreement between you and CKSZ LLC ("CKSZ LLC", "we", "us") for your use of DuoShell for iPhone and iPad, DuoShell Pair for Mac, and the website at duoshell.link (together, the "Apps and Site"). By installing or using them you agree to these Terms. If you don't agree, please don't use them.

1. What DuoShell Is

DuoShell is an SSH app: it connects your iPhone or iPad to servers you choose and runs the commands you send. DuoShell Pair is a free Mac app that uses your Mac's own SSH access to add your iPhone's or iPad's public key to the servers you pick. We may improve or change features over time.

2. Beta Software And TestFlight

DuoShell is in beta and is distributed through Apple's TestFlight. Beta builds may have bugs, may change or remove features, and stop working after a period set by Apple. Apple's TestFlight terms also apply to your use of TestFlight. Keep another way to reach your servers (for example a password or another SSH app) rather than relying on a beta as your only access.

3. Price

DuoShell and DuoShell Pair are free during the beta. If a later release (for example on the App Store) has a price, we'll announce it before you're charged anything, and the App Store's own terms will apply to that purchase.

4. DuoShell Pair For Mac

DuoShell Pair is free to download from duoshell.link/mac. It is signed with our Developer ID and notarized by Apple. It acts only on the servers you check, using the SSH access your Mac already has, to add or remove the public key of the iPhone or iPad you pair. Check the published SHA-256 if you want to confirm your download is the one we released.

5. Your Servers And Your Commands

You are responsible for the servers you connect to and for having permission to use them, for the commands you run, the files you change, the keys you add or remove, and for keeping your own backups. DuoShell sends what you tell it to send; we can't undo changes made on your servers. Read commands before you run them, especially ones you paste.

6. Acceptable Use

Don't use the Apps to access systems you aren't authorized to access, to attack, disrupt or overload any system, or to break the law. Don't try to get around the Apps' security protections, such as the matching code shown during pairing or the server identity checks.

7. Your Data

The Apps have no account and don't send your data to us. Your server list and snippets sync through your own iCloud account; keys and saved passwords stay on your devices. The Privacy Policy explains exactly what is stored where.

8. License

We give you a personal, non-exclusive, non-transferable license to use the Apps on Apple devices you own or control, under these Terms and, for apps downloaded from the App Store, Apple's standard Licensed Application End User License Agreement. Open-source components in the Apps remain under their own licenses. We keep all other rights: don't sell, rent or redistribute the Apps except as those licenses allow.

9. Feedback

If you send us feedback or suggestions (by email or through TestFlight), we may use them to improve DuoShell without owing you anything.

10. Third-Party Names And Services

Apple, iPhone, iPad, Mac, TestFlight, iCloud and Face ID are trademarks of Apple Inc. 1Password and Tailscale are trademarks of their respective owners. DuoShell is an independent product and is not affiliated with or endorsed by them; it names them only to describe what it works with. Their services have their own terms.

11. Availability And Warranty

We work to keep the Apps and Site working, but we don't promise they will be uninterrupted or error-free. To the extent the law allows, they are provided "as is" without warranties of any kind.

12. Limitation Of Liability

To the extent the law allows, CKSZ LLC is not liable for indirect, incidental or consequential losses, or for loss of data, profits or business, including changes made to your servers through the Apps. Our total liability for any claim relating to the Apps and Site is limited to the greater of the amount you paid us for them in the 12 months before the claim arose and US$50.

13. Ending

You can stop using the Apps at any time: delete them, and remove their keys from your servers (Help explains how). We may stop offering the beta or the Apps.

14. Changes To These Terms

We may update these Terms. If a change is material we'll say so here and change the date above, and where we can, tell you in the app or by email. Continued use after the change means you accept it.

15. Governing Law

These Terms are governed by the laws of the Commonwealth of Pennsylvania, USA, without regard to conflict-of-law rules. Any dispute relating to these Terms or the Apps and Site will be brought exclusively in the state or federal courts located in Pennsylvania, and you consent to their jurisdiction and venue.

16. Contact

Questions about these Terms: [email protected]. DuoShell is made by CKSZ LLC.