Solarium - PHP Solr client. Of-course the main focus of this website is to show to benefits of using Solarium.
However, it’s probably just as important to also tell you what not to expect of Solarium and when you might be better of using another solution. What Solarium doesn’t have User interface components.
Lucene - Apache Solr. Elasticsearch - - Open Source, Distributed, RESTful, Search Engine.