There may be a free CS course out there that teaches how to implement a simplified version of Google's PageRank. It's essentially just the recursive idea that a page is important if important pages link to it. The original paper for it is a good read, too. Curiously, it took me forever to find the unaltered version of the paper that includes Appendix A: Advertising and Mixed Motives, explaining how any search engine with an ad-based business model will inherently be biased against the needs of their users[0]

[0] https://www.site.uottawa.ca/~stan/csi5389/readings/google.pd...