Earlier quoted context omitted.
With only ~11,000 entries and what looks to be a pretty defined set of searchable fields, it should be a simple setup. I'd guess the search is powered by either Elasticsearch or Postgres/MySQL. I think the more interesting part of the product is going to be the procurement of available servers which I don't have any guesses outside of public API's + web scraping to do that.
What was interesting to me is the search ID, https://www.serverhunter.com/?search=157-857-0B2 for example. Each change results in a new search ID. If you toggle the same option on and off, the search ID is different every time. I originally thought it was a way to reference a unique combination of the facets but it seems to create a new search session for each query.
We might replace it with something that doesn't require the backend at all, but the URLs will end up quite long if you have a few filters selected.
For now, we figured a short URL is nicer to share with other people. :)