Home / Guides / How to run two instances of the same app on Mac

How to run two instances of the same app on Mac

Published Aug 8, 2026 · Updated Oct 25, 2026

“Run two instances” usually means one of two different things: two windows of one account, or two fully separate accounts running at the same time. Here's every real way to get either, and which is which.

Two windows vs. two accounts — decide which one you need first

If you just want a second window of the app you're already signed into — a second Slack window pinned on another desktop, say — most apps already support that from their own Window menu, no special approach required. What actually gets asked here is almost always the harder version: a genuinely separate account, signed in independently, open at the same time as the first, without logging one out to use the other.

If you came here asking how to duplicate an app — copy it in Finder with ⌘D — that is a narrower question with its own answer: how to duplicate an app on macOS, and why a Finder copy doesn't give you a second account. This guide is about getting a second, separate account running.

The five approaches below solve that second problem to different degrees. None is universally best — the right one depends on how often you switch and how separate you actually need the data to be.

Terminal: open -n

open -n -a "AppName" tells macOS to launch a fresh process instead of activating one that's already running. For apps that don't defend against it, this genuinely gives you a second process — but not a second account, because that process still reads the same on-disk data directory as the first. A large share of apps refuse outright, too: Electron apps in particular commonly lock against a second instance, so the new process just forwards its launch to the first and exits. Full mechanism in the dedicated guide.

Best for: apps that don't single-instance-lock, when two windows of one account is genuinely what you wanted.

A second macOS user account

System Settings → Users & Groups → Add Account gives you a completely separate home directory — the most thorough isolation macOS offers, because it isn't a workaround, it's what user accounts are for. The cost is that it's a full login: Fast User Switching keeps both sessions running, but switching is a slower, heavier context switch than ⌘Tab, and you can't see both accounts' windows on screen at once.

Best for: a hard boundary you rarely cross — a shared family Mac, or a machine used for one employer's work and nothing else.

Browser profiles

If the account you need a second of lives on the web — Gmail, most SaaS tools, anything you'd normally reach at a URL — browser profiles are the cheapest real answer. Chrome, Firefox and Edge all support adding a second profile with its own cookies, extensions and login, open in separate windows at the same time. This only covers things you access through the browser: a native desktop app built around the same service doesn't inherit browser profile switching, because it isn't a browser tab.

Best for: web-based accounts, when you don't specifically need the native desktop app.

A virtual machine

Parallels or UTM gives you an entire second macOS instance, which trivially solves the isolation problem because it's a different computer as far as any app is concerned. It's real, and it's also the heaviest option by far — a meaningful chunk of RAM and disk set aside permanently, and a full OS to keep updated, usually for a single app's second login.

Best for: isolating more than one app at once, or an OS version the host can't run natively.

A real second copy, with its own identity

A copy of the app that macOS treats as a different app: its own identity, its own data, both signed in and open side by side, each with its own Dock icon. It's the only approach here that does that for a desktop app without switching users or running a second OS. A Finder copy isn't it — the duplicate guide explains what has to change — and doing it by hand is tedious work per app; tools like MacDupl automate it in a couple of seconds. For ready-made combinations, see example setups.

Best for: apps you switch between constantly and want both open permanently, without ever logging out.

Which kind of app are you dealing with?

Which of the approaches above works depends on how the app is built, and you can check that in a minute. Right-click the app in Finder, choose Show Package Contents, and look inside Contents:

• Electron apps (Slack, Discord, Notion, VS Code and many more) have Frameworks/Electron Framework.framework. They usually hold a single-instance lock, so open -n does nothing, but most accept --user-data-dir, which is the handle a second account needs.
• Chromium browsers (Chrome, Brave, Edge, Vivaldi) have built-in profiles. If a profile is enough, use it; you only need more when you want separate extensions, a separate Dock icon, or both open as separate apps.
• App Store apps have a _MASReceipt folder. They're sandboxed, and their data sits in a container tied to the app's identity, so a plain copy can't be separated from the original. If the vendor also offers a direct download from its own site, that build is usually the one to use.
• Everything else is a native app. Each one decides for itself where it keeps its data and whether it allows a second instance, so the quickest test is open -n: no new window means it locks; a window signed into the same account means it doesn't lock but shares its data.

Compare them side by side

Questions