Add tags to contacts

Okay, I know that's perhaps not quite the focus of AuthoredUp.
But it would be extremely helpful if you could assign your own tags to your contacts.
That would be clear:
Have I already sent the contact an InMail?
Should I get in touch with the contact again?
Is the contact already a customer?
AuthoredUp is extremely well and robustly programmed.
It would be great to have an equally robust tagging function for contacts.
Thank you very much!