How to avoid registration spam?

Question

Software design

There is some system on the web that has free registration. The username and password are set for the user.
Question - what practices exist to avoid spam registrations?
As far as I understand, activation via email, captcha, binding to ip, etc. manage pretty easily. Did you come up with something instead?

Answer 1

Manual identification of a person (that is, limit the functionality until verification is passed)
For verification, for example, a photo of the first page of a passport with partially smeared data and needed)
Or verification in the form of a selfie
Or KYC ( https://bytwork.com/articles/kyc#toc--kyc )
A lot of things come down to providing any documents, otherwise everything is much easier
Depends, of course, from the project. If this is a store selling something illegal, then it's better to let the bots fight.
You can also just clean (or ban) those who have recently registered and are not active.
What is your project? From this it will already be possible to dance which options may be more acceptable

Answer 2

And if you do not give the opportunity to register an account until the user confirms the registration from the letter ( double-opt-in ) in the box that he leaves when filling out the form. Or is this method also now easy to bypass?