Prerequisites

Offsite checks most of this for you: the Set up This Mac screen shows a health check with one-click fixes. This page is the reference for what those checks expect, and for setting up remote hosts, where you prepare the machine yourself.

Mac as host (“This Mac”)

Requirement	Details	Offsite helps
Apple Silicon Mac	M1 or newer; host artifacts ship for macos-arm64	—
macOS 26 (Tahoe) or newer	The Mac app targets macOS 26.0	—
Command Line Developer Tools	Provide real git and python3 (a bare Mac only has stubs). Roughly 2–3 GB	Health check row with an Install… button; setup continues automatically
Homebrew — or tmux installed any other way	Sessions run inside tmux; Offsite installs tmux via brew automatically	Health check row: one click copies the official brew.sh command, opens Terminal, and setup continues once done
At least one agent CLI	Claude Code, Codex CLI, or Grok CLI — installed and logged in	Setup shows an Agents row with guidance
Network access	offsite.sh (app download + updates) and get.offsite.sh (host components) over HTTPS	Health check row verifies the update server

Explicitly NOT required: macOS Remote Login (System Settings → Sharing), SSH configuration of any kind, an admin password for the standard setup. Offsite runs the local host directly and connects through its own embedded agent, so port 22 can stay closed.

Optional (asks for admin once): “Always reachable” installs the agent as a LaunchDaemon so the host survives reboots and runs before login.

Remote Mac as host

Everything from the table above, plus:

• Remote Login enabled (System Settings → General → Sharing → Remote Login) — the initial install runs over SSH. After setup, sessions use Offsite’s embedded agent.
• Reachable from your Mac via SSH (LAN, Tailscale, or public address).

Linux as host

• SSH access (key or password) to the machine.
• python3, plus curl or wget (present on almost every distribution; minimal Debian images may need apt-get install curl).
• tmux and git — installed automatically via apt/dnf/yum/pacman (needs sudo) if missing.
• systemd user session for the Offsite agent; for “always reachable” also loginctl enable-linger <user>.
• At least one agent CLI (Claude Code, Codex CLI, or Grok CLI), logged in.

iPhone / iPad app

• iOS 18 or newer. During the private beta the app comes with your invitation; at launch it ships through the App Store.
• Pairing happens with the QR code or the host code shown during host setup, with no account required.

Disk space (rule of thumb)

What	Size
Offsite app (DMG)	~160 MB
Host components (runtime, agent, helpers)	~120 MB installed
Apple Command Line Tools (if missing)	~2–3 GB
Homebrew + tmux (if missing)	~1 GB

Next

Install & set up walks through the actual setup, and What macOS will ask you lists every system dialog you may see along the way.