Install Cosmos on macOS

Installing Cosmos on macOS takes two steps: download the .dmg, then drag the app into /Applications and open it. Cosmos is currently an alpha macOS build; public notarized distribution is the target for the polished public release.

Before you start

• Apple Silicon (M-series) is the primary, fully supported target. Intel Macs and other operating systems are in development.
• You need the latest Cosmos .dmg download. Current alpha build: v0.2.29-demo.

1. Download Cosmos

Download the latest .dmg from the Download button or releases page. Alpha builds are signed for local testing, but may not be Apple-notarized yet. If macOS asks for confirmation, use the fallback below.

2. Install the app

Open the downloaded .dmg and drag Cosmos.app into your /Applications folder, just like any other Mac app.

3. Open Cosmos

Open Cosmos from /Applications, Launchpad, or Spotlight.

open /Applications/Cosmos.app

After the first successful open, you launch Cosmos normally from Launchpad or the Applications folder.

What if macOS still blocks the app?

If macOS reports that it cannot verify Cosmos, right-click Cosmos.app in /Applications, choose Open, then confirm. If that still fails, use the fallback in Troubleshooting. Public notarized builds should not require xattr.

Which Macs are supported?

Apple Silicon (M-series) is the primary, fully supported target. Intel Macs and other operating systems are in active development.

Is the old xattr fallback safe?

Yes, when it is needed for an alpha build you trust and downloaded from the official Cosmos link. xattr -cr recursively clears extended attributes — including the quarantine flag — on the app bundle you just installed. It does not modify the app's code or your data.

macOS still says Cosmos can't be opened — what now?

Confirm that you downloaded the newest .dmg from the official Cosmos site. If right-click Open does not work, see Troubleshooting or contact support with the exact macOS warning text.