How to run two copies of an app on a Mac
macOS runs one copy of most apps per user, and a second copy of the same app shares the first one's sign-in and data. To have two accounts open side by side, the second copy needs data of its own. Here's every way to get that on a Mac, what each costs, and where each falls short.
Facts about other apps checked against their own sites on October 4, 2026.
The short answer
For two accounts on a website, a second browser profile is free and usually enough. For two accounts in a Mac app (Slack, WhatsApp, Discord, Claude, Teams), you need either a second macOS user account, where you see one account at a time, or an app that makes separate instances of other apps, like Parallex or Parall, where both stay open side by side.
Every way, side by side
| Way | Both open at once | Separate sign-in and data | Mac apps, not only websites | Cost |
|---|---|---|---|---|
open -n in Terminal | Sometimes | No, except Chrome and VS Code given their own folder | Yes | Free |
| A second macOS user account | No, one account on screen at a time | Yes, everything is separate | Yes | Free |
| Browser profiles | Yes | Yes, for websites | No | Free |
| The web version in another browser | Yes | Yes | No, only services with a website | Free |
| The app's own account switcher | Depends on the app | Within the app | Yes, where the app has one | Free |
| Parall | Yes | Yes for Electron, Chromium and Firefox apps and some others; WhatsApp and Teams as web apps | Yes | $9.99 once, Mac App Store |
| Parallex | Yes | Yes, with its own keychain and Dock icon | Yes, App Store apps included | Free to try |
1. Terminal: open -n
open -n -a "Slack" asks macOS for a new instance of an app even when one is running. What happens next is up to the app. Many apps allow only one running copy and hand over to the first, so nothing new opens. Those that do open twice read the same data folder, so the second one is signed in to the same account, and two copies writing one folder can damage it.
Chromium browsers and VS Code are the exception: they take a folder of their own with --user-data-dir, as in open -n -a "Google Chrome" --args --user-data-dir="$HOME/Chrome Work". That works, but it's a command to type each time, and both share one Dock icon, so it's hard to tell which window is which.
Duplicating the app in Finder doesn't help either: the duplicate has the same identity as the original, so it reads the same data, and it falls behind when the original updates.
2. A second macOS user account
System Settings › Users & Groups › Add User makes an account with its own home folder, so every app in it has its own data, and Apple's own apps get their own Apple Account. With fast user switching (System Settings › Control Center) you can switch without logging out.
It's the most complete separation macOS has, and it's free. But you see one account at a time: the other account's apps keep running, out of sight, until you switch to it. Files, settings and the Dock are separate too, which is the point on a shared Mac, and in the way when you only wanted a second Slack. Parallex or a second user account.
3. Browser profiles
Profiles in Chrome, Edge, Brave and Firefox, and in Safari since Safari 17, each keep their own cookies, history and extensions, so you can be signed in to two accounts of the same website in two windows of one browser. For services you only use in a browser, that's often all you need.
Profiles separate websites, not Mac apps: they don't help with the Slack, WhatsApp or Claude app. In Chrome, a link you click in another app opens in whichever profile you used last. Parallex or browser profiles.
4. The web version, in another browser
Slack, WhatsApp, Discord, Telegram, Teams, Notion, Figma, Claude and ChatGPT all have a web version. Keep the app for one account and the website for the other. On macOS Sonoma and later, Safari's File › Add to Dock turns a site into a web app with its own Dock icon.
It's free and it works. The website is one more browser window, though, with what the web version has, which isn't always all the app does. Parallex or the web version.
5. The app's own accounts
Some apps handle several accounts themselves: Slack keeps every workspace you sign in to, Telegram and Discord switch between accounts, and Discord's test builds (PTB and Canary) install beside the regular one with their own sign-in. VS Code's profiles separate settings and extensions, not accounts. When the app's own way is enough, use it: it's built in.
It falls short when the accounts need to stay apart, with both visible at once and notifications you can tell apart, or when the app only signs in to one account at a time, as the Claude and WhatsApp apps do.
6. An app that runs other apps twice
Parallex and Parall both make instances of other Mac apps that run beside the original, each with its own data. Parallex gives an app either an instance that starts it with a data folder of its own, or its own copy with an identity of its own: its own Dock icon, notifications, macOS permissions, Library and keychain, which is also what lets App Store apps like WhatsApp run twice. Parallex and Parall, side by side.
Others make copies too: MacDupl (APFS clones, $19 once after a 3-day trial, macOS 13 and later) and Parallel Spaces ($4.99 on the Mac App Store, macOS 14 and later), and for Claude alone, Multi-Claude. Apps like Ferdium, Rambox and Wavebox are different again: they gather the web versions of several services, with several accounts each, into one window.
Which to choose
- Two accounts on a website you use in a browser: a browser profile.
- A shared Mac, or a whole separate setup with its own files: a second user account.
- Two accounts of the same Mac app, open side by side: Parallex (or Parall).
- Only Chrome or VS Code, and happy in Terminal:
--user-data-dir.
A guide for each app
How a second copy goes with the apps people ask about most, each with what the app already does by itself:
Questions
Why does opening an app again just bring back the same window?
macOS keeps one running copy of an app per user: opening it again brings the running one forward. Even with open -n, many apps notice the first copy and hand over to it.
Can I run two copies of an App Store app?
Not with open -n: App Store apps are sandboxed, and both would use the same container. A copy with an identity of its own gets a container of its own. Parallex makes those, including for apps like WhatsApp that keep their data in containers shared with the developer's other apps.
Is there a Sandboxie for Mac?
Not in the Windows sense. macOS has its own app sandbox, which App Store apps run in, but nothing that wraps any app in a throwaway sandbox. Parallex separates an app's data so it can run twice; its Guard keeps a copy out of the original's data, but it's a safety net, not a security sandbox. For software you don't trust, use a virtual machine.
Does a second copy slow the Mac down?
A second copy uses about as much memory as the first while it runs. On disk, Parallex's copies are APFS clones, so they share most of their space with the original.
Get Parallex
Free to try, for macOS 14 and later. In Terminal:
curl -fsSL https://parallex.mandip.dev/install | shOr download the disk image, or with Homebrew: brew install --cask mandipadk/parallex/parallex.