If you want to transfer your domain from ZEIT to an external registrar, you can do so by following the steps below.
ICANN rules state that a domain must have been held by the same registrar for 60 days before it can be transferred. This includes both cases where the domain was registered with ZEIT originally and where it has been transferred into ZEIT.
Once you have verified your domain is eligible for transfer, you should contact the support team at email@example.com. Once you have reached out, a member of the support team will first verify your identity and ownership of the domain before providing you with an authorization code.
Your authorization token is used by your new domain registrar to confirm your identity and process a domain transfer to them from ZEIT.
After receiving the authorization code, you may provide it to your new domain registrar who will then be able to process the transfer in for you. Your new domain registrar should provide you with the steps for completing your transfer in, this is commonly done in a user control panel.
Domain name transfers are usually completed very quickly, often within minutes, however, in some situations this can take longer for which you should speak with your new domain registrar about.