Windows SmartScreen blocked the download

Two minutes. Two clicks. You will not need to disable anything permanently.

Why this happens: Nimbus is a niche tool with a very small install base. Microsoft's SmartScreen reputation system flags every new release until thousands of users run it. This is normal — it does not mean the file is unsafe. The binary's SHA-256 hash is published on /dashboard/download so you can verify before running.

Step 1 — Save the file

When your browser warns about the download, click Keep (Chrome / Edge) or Keep anyway (Firefox). On Edge the dropdown may say “NimbusLoader.exe was blocked because it could harm your device.” — click the three-dot menu next to it and pick Keep → Show more → Keep anyway.

Step 2 — Run past SmartScreen

Double-click the saved NimbusLoader-*.exe. A blue panel will appear:

Windows protected your PC

Microsoft Defender SmartScreen prevented an unrecognized app from starting. Running this app might put your PC at risk.
App: NimbusLoader-w814.exe
Publisher: Unknown publisher

Don't run

More info

Click More info (small text, not the big “Don't run” button). The panel will expand and a new button will appear: Run anyway. Click it. That's it.

Step 3 — Sign in

Nimbus will open its dark sign-in dialog. Use the same username and password you set up at sign-up, or paste your license key into the username field if you skipped account creation. After this first run SmartScreen will not prompt again on this machine.

SmartScreen still blocks “Run anyway”?

On stricter enterprise policies the Run anyway button is hidden. Right-click NimbusLoader-*.exe → Properties → at the bottom of the General tab check Unblock → OK. Re-run the file. The Unblock checkbox removes the Mark-of-the-Web tag the browser added on download; without that tag SmartScreen does not engage.

Defender quarantined the file

That's a separate antivirus problem, not SmartScreen. See /help/antivirus for the whitelist instructions per vendor.

Back to download Still stuck — open a ticket