When Gearset first connects to a Salesforce org, it requests a range of permissions:
The primary permission that underlies this is the
Modify all data permission. To use Gearset to deploy metadata and data between your orgs, the user (actually, your user's profile) you use to authenticate against the org must have this permission.
Why does Gearset need this permission?
As a deployment tool, Gearset needs the ability to read and write org metadata and data.
What if I'm not trialling data deployment?
There is an
Administrative Permission named
Modify Metadata Through Metadata API Functions. You may consider configuring the Profile to not have
Modify All Data permission, and only have
Modify Metadata Through Metadata API Functions permission.
Regardless, unless you're using Gearset's data loader, the app will never read or write any org data.
Can I control this access?
Gearset's access to an org can be revoked from within the org at any point by the end user, via the OAuth connected apps settings page.