Whether you're auditing a competitor or recreating a layout, these three methods cover public, private and no-install workflows.
Method A: DevTools
Right-click text → Inspect → Computed → font-family. Great for one element.
Method B: Detector
Paste URL into Website Font Detector to list every family with selectors and sizes.
Method C: Extension
For logged-in pages, the extension reads the live DOM (guide linked).