How to open two instances of the same app on a Mac
Macs open one copy of each app and give it more windows. When a second copy helps, the Terminal command that starts one, and why a new window is usually better.
Can I run two copies of an app on a Mac?
Yes, from Terminal:
open -n -a "TextEdit"The system describes -n as opening a new instance even if one is already running. A second icon for the same app appears in the Dock while both run.
Should I use a second copy or a second window?
A second window, in almost every case. Press ⌘ N in the app. Windows of one app are already independent to work in; see a new window of the same app.
A second copy only helps when an app allows one account or one setup per copy, and it must support it: many apps share their settings between copies, and two copies writing the same files can overwrite each other's changes.
How do I keep two browser accounts separate?
Use profiles instead of copies. Safari and Chrome both keep separate history, cookies and sign ins per profile, each in its own windows.
Moving between windows of one app: Command backtick. Lots of browser windows: many Chrome windows.
Checked on 22 October 2026 on a MacBook Air (M1) running macOS 27.0.1: the open command describes -n as opening a new instance even if one is already running.
Questions
How do I open two instances of the same app on a Mac?
Run open -n -a and the app's name in Terminal.
Why does clicking an open app not open a new copy?
macOS runs one copy of each app and brings it forward. Press Command N for a new window.
Is it safe to run two copies of an app?
Only if the app supports it. Some apps share files between copies and can overwrite changes.
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