This chapter aims to demystify the jungle of alternatives, giving a clear and pragmatic overview of the features supported by each solution, with a focus on the most comprehensive and established ones. Given the author’s background in the Apache Lucene and Solr communities, there will be a bigger emphasis on Lucene-based search technologies. The chapter closes with an overview of the features supported by some of the new vector search engines, to check how far they are from the rest.