By what signs can one site user be distinguished from another in order to avoid winding up votes (Without authorization and entering email / phone)?

Question

Survey tools

How to implement voting on your site so that you can vote for one position only 1 time for each user.
If you check by IP, then problems with users behind NAT, cookies and user-agent can be faked ..
Maybe there is an online service with an API for this kind of task.

Answer 1

It's practically impossible. But if your cheaters are ordinary users, try evercookie .

Answer 2

there is no such possibility. the client can fake anything. but he can put spokes in the wheels of sms on the phone. even email confirmation is no longer relevant

Answer 3

Maybe there is an online service with an API for this kind of task.

There are such services called social networks. Get the VK user id and that's it, the second time he won't vote.