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Quality

How Conn is tested.

Conn controls machines people rely on, so it's built to be dependable and careful with your data. Here's how it's tested, and what we haven't done yet.

Figures as of October 2026.

How stable it is

  • Conn has been on the App Store since 13 October 2026, with two fix releases since.
  • Every release is built from code that passes its tests, with zero compiler warnings. A warning fails the build.
  • When something does go wrong, Conn says what happened, why, and what to try, rather than failing silently. Every message is explained in Troubleshooting.
  • With tmux, a dropped connection doesn't lose your work: the session keeps running on the machine, and Conn reattaches.

Automated tests

  • About 4,800 tests on iOS and 4,400 on the Mac in each full run, plus each library's own tests: SSH, the terminal, VNC and the cryptography.
  • Real servers, not mocks. Tests run over the network against a separate machine running OpenSSH (including a hardened setup), SFTP, and the VNC servers TigerVNC, x11vnc, TightVNC and WayVNC.
  • Every fix starts with a failing test. Then the bug is put back on purpose, to prove the test catches it, before the fix goes in.

Hands-on testing

  • A written regression suite of over 1,400 cases, each something a person does in Conn, run on simulators and on real iPhone, iPad and Mac, and worked through release by release.
  • Real machines on the other end: Macs on macOS 26.7 and 27, a Raspberry Pi 4 on Raspberry Pi OS, and Debian 12 and 13. The exact versions are listed in What Conn supports.

Secure by design

  • No account, no Conn servers, no analytics. Conn connects straight to your machines, and nothing of yours passes through us.
  • Keys made in Conn live in the Secure Enclave, where the device has one, and can't leave the device.
  • Passwords stay in the Keychain on that device only. Saved SSH and Mac passwords need Face ID or Touch ID each time they're used.
  • Every server's SSH key is checked, with a clear warning if it changes. Like ssh, Conn trusts a server's key the first time it connects.
  • Port forwards listen on the device itself only, so nothing else on your network can use them.
  • The Mac app is sandboxed, and test-only code is compiled out of release builds.

The details are on the Security page.

Security reviews

In October 2026, seven code reviews went through the sensitive parts of Conn:

  • secrets and iCloud sync;
  • the data store and upgrades;
  • anything that deletes;
  • untrusted input from servers;
  • trust and networking;
  • privacy;
  • the app's lifecycle.

A second reviewer confirmed every serious finding. Between them they found 4 high, 8 medium and 27 low issues. All of them are fixed, each with a test, in the releases since.

A separate review of the cryptography and host trust code found no high or medium issues.

These were AI-assisted code reviews, each with a second reviewer. No third-party penetration test has been done yet.

Keeping it that way

  • The libraries Conn uses are checked every month for security advisories.
  • New fixes keep the same rule: a failing test first, then the fix.
  • Found something? Please tell us. How to report a security problem, and what we promise in return, is on the Security page, with security.txt for the machine-readable version.