Peak is a sandboxed Mac App Store app. By design it can read only the one folder you explicitly point it at — it has no access to the rest of your disk. The first time you open Peak, it asks you to choose your iPhone backup folder. You do this once.
iPhone backups live at ~/Library/Application Support/MobileSync/Backup/. A sandboxed app can't open that folder on its own; you grant access by selecting it yourself. This is a deliberate privacy boundary: Peak literally cannot look anywhere you don't choose.
On first launch, Peak shows a "Choose your iPhone backup folder" screen with a Choose Backup Folder… button.
~/Library/Application Support/MobileSync/Backup/macOS remembers your choice (via a security-scoped bookmark), so you won't be asked again on later launches. Peak then shows your iPhone backups in the left sidebar.
Only what's inside the folder you selected:
sms.db and the message attachments for the threads you scanAddressBook.sqlitedb from the backup itself, to resolve phone numbers to contact names — Peak never touches the Mac's own Contacts appPeak reads nothing else on your Mac — it can't, because it's sandboxed. There's no analytics, no telemetry, and (because it ships through the App Store) no network calls at all.
Drag Peak to the Trash. A sandboxed app's folder grants are tied to the app, so removing the app removes its access to your backup.
Next: Working with Encrypted Backups or skip to Reading the Report.