A while back I open-sourced the code for the WbSrch search engine.
It’s online now in a much-reduced form at wbsrch.com.
It’s not the full search engine. Far from it. It’s just a tiny database of about 10,000 or so URLs to demo the source code, but it’s possible you’ll actually find what you’re looking for in even that tiny amount of data if your search is sufficiently simple.
It probably won’t get any bigger — that’s about the size I can support “for free”, in that it doesn’t take enough resources on my inexpensive VPS to impact more important things. If you’re curious what the original WbSrch search engine was like, it’s a pretty good demo, at least visually.