-
fingerprintjs
Browser fingerprinting library. Accuracy of this version is 40-60%, accuracy of the commercial Fingerprint Identification is 99.5%. V4 of this library is BSL licensed.
-
SurveyJS
Open-Source JSON Form Builder to Create Dynamic Forms Right in Your App. With SurveyJS form UI libraries, you can build and style forms in a fully-integrated drag & drop form builder, render them in your JS app, and store form submission data in any backend, inc. PHP, ASP.NET Core, and Node.js.
With a sticky fingerprint. I’ve built a system like this for managing trolls. You fingerprint the user and associate it with an IP. There are multiple mechanisms that can contribute to the fingerprint (cookie, user agent, supported media codecs, etc. See https://github.com/fingerprintjs/fingerprints for an example implementation).
Then if another user registers with the same fingerprint we link the accounts together.
In our case the whole thing is also requiring human moderator input to actually keep the whole thing going though.