NLP4L is a natural language processing tool written in Scala for Apache Lucene. The main objective of NLP4L is to use NLP (Natural Language Processing) and machine learning technologies to improve the search experience of search engine users. “4L” in NLP4L means “for Lucene” and specifically targets search engines Lucene-based Apache Solr and Elasticsearch.


provide preprocessing platform for Lucene indexing and comprehensive Learning-to-Rank modules


a collection of Apache Solr plugins that collaborate with NLP4L/nlp4l