Client: Lets put on a voting there. That can shows the popular one!
Us: How do you wanna vote?

When marketers want to have “engagement” and “popularity index”, voting is “the mechanic” to go. But not so much by digital marketer though.
The Identity Problem
Voting alone is not hard, but it always has a fundamental element that got overlooked: each person can only vote once. The hard part comes from identifying “person” is exactly one person.
That are two sides to balance: effort to identify and amount of spam.
We are going to show a few solutions to the problem, pros and cons.
Cookies (or, “sessions”)
TL;DR Transparent to user, easy to do, very easy to spam votes
Cookies can record user information on user’s browser. Thus can limit the vote by browser. This method is almost transparent to user. No extra fields to fill, just click and forget.
But user can have a few browsers at hand. And the introduction of “private mode” in modern browsers make spamming even easier. Private browsers do clear cookie, means voting in each new private tab.
IP
TL;DR Transparent to user, easy to do, flaw in votes
Each “node” on the internet have a unique IP address. This sounds the perfect solution: transparent to user, uniqueness by default, and secure.
But my brother, mum and dad all uses the same IP at home. After my vote, they can’t. Even worse, mobile users of the same operator within a certain area shares the same IP as well. This solution is becoming “non-workable” solution due to the domination of mobile usage.
Email
TL;DR Relative easy to do, easy to spam votes
Entering email when voting. Sounds easy enough when heard, but extra keyboard interactions means drop in conversation. Also, mocking a email address is easy, throwaway email accounts is just a few clicks away. Verify the email? Further drop in conversation.
Login with Facebook/Twitter/weibo/Google/any_modern_social_media
TL;DR Hard to do, unique votes
Single sign-on (SSO) means a social profile can only vote once. But “login” to vote sounds too much.
Offloading the identity problem is a reasonable choice, but SSO itself is hard. Oauth(communicate with social media) is hard, authentication is hard.
Like button
TL; DR easy to do, unique votes, cannot fake counts
Facebook’s like button is actually a valid option. User can only like once in lifetime, identification is done by Facebook. The real drawback is, project owner do not have any control. You cannot add artificial count, cannot bump your own choice, you have no control.
And user need Facebook account to “vote”.
How to pick?
You can ask yourself these questions to pick the best fit solution to your campaign:
How fair I need to guarantee unique votes?
How much budget I have?
Will user overcome the troubles to vote? (incentive driven?)
It is easy to say that like button is the cheapest and easiest to do, followed by cookies. IP is slightly cheaper than email, social login is most expensive.
Still confused? we can help you!