Amber acts as an extension to sign for your private key instead of plugging in your nsec into all the apps you want to try out.

Amber signs for your nsec to all the apps you want to try.

If you go to nostrapps.com it's on there. You can download> copy paste your nsec I to amber> log out of all the nostr apps> open them with Amber running, and it will ask you to sign for each app to log in that way.

Ita much safer for your nsec security.