What is Solr?

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An open source search server based on Apache Lucene

Apache Solr, based on Apache Lucene and available under the open source Apache license, powers search for some of the world’s largest organisations including Bloomberg, Best Buy, Sears, Instagram, Ticketmaster and AOL. Solr is highly scalable, resilient and accurate. Solr is built by a group of committers working under a Project Management Committee also made up of committers – these committers come from a wide range of companies both large and small and some are individual consultants (OSC’s Eric Pugh and Kevin Risden are both Solr committers). There is thus no organisation with overall control of Solr, which has its advantages and disadvantages!

Solr is a huge and complex project and there are often several different ways to achieve the same functionality. However it is a well-understood technology that has been available for over 20 years and there is a vast amount of written material, videos, training courses and blogs about Solr.


Pros and Cons of Solr

  • It’s freely available and open source under the non-profit Apache Foundation
  • No one company controls the project
  • The learning curve can initially be steep
  • It is hugely scalable, to hundreds of billions of documents
  • A pluggable architecture allows for flexibility
  • It is a very mature project used across the world by thousands of organisations
  • Written in Java with client libraries available for many other languages
  • Development is rapid with new features being added all the time


We’ve curated a playlist of videos about Solr from our own events and across the Web.

Contact us today for help with your Solr project

We’re recognised experts in Solr and committers to the project – we help build it!

We create and maintain open source plugins, extensions and tools for Solr including Quepid, the test-driven relevancy dashboard and a number of modules available on and our Github.

We teach the craft of Solr relevance engineering through our Think Like a Relevance Engineer Solr training, regular blogs and via our Youtube channel. We run the London Lucene/Solr Meetup and our Haystack conference series which focuses on relevance engineering. Our free Relevance Slack community has over 2000 members and a dedicated #solr channel.