It's a simplified version of what is described here in this article by David Foster. In short, it uses the Google autocomplete API to append "vs" after your term and auto complete the top matches. It does some cleaning to remove duplicates.
It uses a force directed network graph based on the D3 examples here. The rest of the site looks like sh*t partly for reasons similar to this but mainly because of reasons similar to this.
Shout out to this GitHub repository by Anvaka which implements something very similar but which I only discovered afterwards.
You can find the source code here on Repl.it where this project is also hosted.
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