UTM Studio

A native macOS app for spinning up disposable, space-efficient clones of a UTM virtual machine — launch a fresh, identically configured VM in a couple of clicks, let it discard everything on shutdown, and never touch UTM's own window for day-to-day use.

Built around a simple idea: keep one Master VM as the source of truth (OS, apps, settings), and spin up disposable clients from it on demand — each one starts fresh from Master's current state and throws away anything written to it once it's stopped. Useful anywhere you want a clean, consistent, per-session VM — testing, throwaway environments, demos — without paying the disk cost of a full copy every time.

Requirements

• macOS 14 or later, Apple Silicon (M1 or newer). This is enforced, not just untested elsewhere — the app won't launch at all on an Intel Mac.
• UTM installed, with its utmctl command-line tool available (UTM Studio can usually find it automatically; see First-time setup below).
• A Master VM already set up in UTM, using the QEMU backend (not Apple Virtualization), with a .qcow2 disk. This is the VM UTM Studio clones clients from.
• Full Disk Access, granted to UTM Studio in System Settings → Privacy & Security → Full Disk Access. Locating VM files (for cloning a client's disk, and for "Show in Finder") needs it — macOS never prompts for this automatically, so UTM Studio asks you to grant it once, right after first launch.

Features

• One-click disposable clients — create a named clone of a Master VM, launch it, and its disk resets to match Master again next time.
• Space-efficient by design — clones share physical disk blocks with Master via APFS copy-on-write, not a full copy; cloning a 30+ GB disk takes milliseconds and costs near-zero extra space.
• Start non-disposably when you actually want to keep a session's changes — an explicit, confirmed exception to the default behavior.
• Multiple Masters — link different clients to different Master VMs, switch a client's Master later, each Master gets its own view of its own clients.
• Protected VMs — explicitly exclude unrelated VMs in the same UTM library from ever being touched.
• Show in Finder — jump straight to any VM's .utm bundle.
• Menu bar access — start, stop, and create clients without opening the main window; UTM's own window is only needed for editing a Master's hardware or OS-level settings.
• A thin GUI over a standalone script — utm-client.sh does the actual work via UTM's utmctl CLI and is fully usable on its own from the command line; the app is a UTM-styled wrapper around it.
• Update notifications — checks for a newer release on launch and every 24 hours, with a Download/Cancel prompt. Never a forced update.

Install

Grab the latest .dmg from the Releases page, open it, and drag UTM Studio into Applications.

No release available yet, or you'd rather build it yourself?

git clone https://github.com/fbrd-dev/UTM-Studio.git
cd UTM-Studio
./build_app.sh

This produces dist/UTM Studio.app — drag it to /Applications and launch it (right-click → Open the first time, since a self-built copy isn't notarized).

First-time setup

Open the gear icon (Settings) and check/set:

• Master VMs — one or more; each name must exactly match a VM's name in UTM. Add more than one if you want different clients linked to different Masters (see "Multiple Masters" below).
• utmctl — path to UTM's CLI, auto-detected in common locations or set manually if UTM Studio can't find it.

The first time UTM Studio talks to UTM, macOS will ask you to allow it to control UTM — this is a one-time system prompt.

Using it day to day

• Sidebar: your Master(s) pinned at top; every other VM UTM knows about shows up as a client, with a live status dot.
• + button: create a new client — name it, pick a Master if more than one is configured, optionally start it immediately (off by default).
• Row hover play/stop, or the detail pane: start/stop a client. Starting an existing client refreshes its disk from its Master's current state first, automatically.
• Start (Keep Changes): right-click a client, or use the detail pane, to start it non-disposably — this session's changes are saved to its disk instead of discarded, diverging it from Master until you explicitly Relink. A confirmation dialog explains the tradeoff every time.
• Show in Finder: right-click any VM to reveal its .utm bundle in Finder.
• Relink: refreshes a client's disk without starting it — mainly for pre-warming a client, or resetting one that drifted from being booted non-disposable.
• Remove: deletes a client entirely, after a confirmation prompt.
• Push Updates to All Clients (on a Master's detail pane): full re-clone of every client linked to that Master — a slower fallback; normal use doesn't need it, since Start/Relink already keep clients current.
• Open in UTM…: the only time you should need UTM's own window — for editing a Master's hardware or OS-level settings.
• Menu bar icon: the same start/stop/create/push actions, without the main window open.
• Freshness indicator: shows whether a client's disk was cloned at or after its Master's last change — purely informational, since Start refreshes automatically regardless.
• Protected VMs: right-click any client → "Exclude from Master linking…" to take a VM out of reach entirely — worth doing for anything in the same UTM library that isn't actually part of this Master/client setup.

Multiple Masters

Add more than one Master under Settings, and link different clients to different ones:

• Pick a Master when creating a client (shown only once more than one Master exists); switch it later from the client's detail pane or via right-click → "Switch Master" in the sidebar.
• Switching only updates which Master a client is assigned to — the next Relink or Start is what actually clones from the newly-assigned Master.
• Each Master gets its own detail pane, scoped to its own clients.

Learn more

DEVELOPMENT.md covers the architecture, the reasoning behind some of the less obvious design choices, and how to sign/notarize your own build — worth a look if you're curious how it works under the hood or want to contribute.

License

MIT.