Mass label contacts

[arturritzel]

I want to mass label hundreds of contacts but couldn't find a way to do it. Maybe using an specific API endpoint?
Is it possible to import contacts with labels? When I export contacts I see there are fields for id, name, email, phone number, but couldn't find a way to import contacts with labels. Also, how should my contacts csv look like when importing contacts? I assume I should not define an id for contacts, for example.