registration - Only providing social logins

I'm currently working on a project where the user is required to register, and we are considering only providing social logins, and not providing a site only registration.

The reason behind this is that the data we will be storing for the user is trivial, and the only sensitive thing would be email and password. However if we use social logins this data is handled for us by the 3rd parties.

This means that we would not need to purchase a SSL Certificate for the website and save money on something that is a hobby/passion project.

We believe if we provide a decent spread of social logins that 99% of the audience will be covered anyway. We are also mindful not to overload the user with too many choices, so were thinking of providing: Facebook, Google+, Twitter, Microsoft

Would this cause a negative effect on sign up rate? Are these sites the optimum 4 to reduce overload, but cover the audience?

Answer

For your specific question on which social logins to use, it depends on your users/market.

However, Facebook is by far and away the most important one, followed by Google. Then a mix of Twitter, LinkedIn and Yahoo.