Install & set up
Setting up Offsite is three moves: install the Mac app, let it set up This Mac as a host, then pair your phone. Nothing here needs an account.
Before you start, skim Prerequisites, especially if this is a fresh Mac.
1. Install the Mac app
Section titled “1. Install the Mac app”Download the app from offsite.sh, open the DMG and drag Offsite into your Applications folder. The app is signed and notarised by RapidRocket GmbH, so macOS opens it without a Gatekeeper detour.
2. Set up This Mac
Section titled “2. Set up This Mac”On first launch, choose Set up This Mac. The setup screen runs a health
check and then installs the host components into ~/.offsite. Each row is
either already green or carries the button that fixes it:
| Row | What it checks | If it is red |
|---|---|---|
| Developer Tools | Apple Command Line Tools — the real git and python3 |
Install… starts Apple’s own installer. Setup waits and continues by itself. |
| Homebrew & tmux | Sessions run inside tmux | One click copies the official Homebrew command and opens Terminal. Paste, run, and setup picks up from there. tmux itself is installed for you. |
| Update Server | get.offsite.sh is reachable and the host build is published |
Check your network, then Check Again. |
| macOS Prompts | Nothing — it announces which system dialogs are coming | — |
Two things on this screen:
- Always reachable is optional. Switch it on and Offsite installs its agent as a system service, so this Mac is reachable from your phone after a restart, before anyone logs in. macOS asks for your administrator password once. Leave it off and the host runs while you are logged in.
- Remote Login stays off. Setting up This Mac does not need SSH, does not need port 22, and does not change your Sharing settings.
What macOS will ask you lists every system dialog in the order it appears, and why each one is there.
3. Install at least one agent CLI
Section titled “3. Install at least one agent CLI”Offsite runs the real agent binaries; it does not ship its own. Install and log in to at least one of:
- Claude Code —
claude - Codex CLI —
codex - Grok CLI —
grok
Use each vendor’s own installer and log in once in a terminal. Offsite then finds them and offers them when you create a session; Refresh Agents re-scans after you install one.
4. Pair your iPhone
Section titled “4. Pair your iPhone”Install the Offsite app on your iPhone (iOS 18 or newer), then, in the Mac app, open the host’s ⋯ menu and choose Show iPhone QR. Point the phone at the code.
That transfers the host’s address and its pairing material. Passwords are never part of the code. From then on the phone connects on its own, directly on your network, over Tailscale, or through the relay, whichever is reachable.
5. Open your first session
Section titled “5. Open your first session”Create a session on the host, pick a working directory and an agent, and start typing. The session runs on the Mac inside tmux: close the lid, lose Wi-Fi, quit the app — the agent keeps going, and the output is waiting when you come back.
Adding more hosts
Section titled “Adding more hosts”The same app sets up other machines too — another Mac over SSH, or a Linux server. Those paths need a bit more of the machine up front; see Prerequisites.