Hi,
Check IP Address, if this option not used, how much/which one among Fingerprint, tracking data & cookie option is reliable to prevent unfair voting? Also, what is less sensitive (in case of data breach and privacy concerns) among them to use for contests. Obviously you can its our choice which one to use, but as you people are more experienced in this, i want your views on it.
Also,
this is not part of your services but can you suggest some server options or data protection techniques which are more relible to use to run contest. this information may be useful for many of us using your extension to run a successful voting contest website for long term.