Hreflang on multiple domains
I need some help and guidance regarding Hreflang tag.
We are working on a website, say example.com. We are planning to launch the same website in the german language with different domain - example.de. The content should remain the same on the .de website.
We don't want to get into the Google penalty for duplicate content. How can I use hreflang tag on both of the websites?
I am confused using the hreflang tag on both websites. Should I need to add both tags on two domains?
I'd appreciate your thoughts. Thanks guys