upn — User Principal Name

Location: payload · Vendor: Microsoft Entra

The user's sign-in name in user@domain form. It is mutable (renamed on directory changes) and, per Microsoft's own guidance, increasingly superseded by preferred_username for display purposes — don't use it as a stable key.

Defined in Microsoft identity platform token reference.

Decode a JWT and inspect its upn claim in the TokenPrism debugger — free, entirely in your browser.