OpenSearchServer is described as 'Open source application server allowing development of index-based applications like search engines. Main features of OpenSearchServer are : An integrated crawler for databases, web pages and rich documents; a user friendly GUI allowing development of most' and is a Search Server in the development category. There are more than 25 alternatives to OpenSearchServer for a variety of platforms, including Web-based, Self-Hosted, Linux, Mac and Windows apps. The best OpenSearchServer alternative is Algolia. It's not free, so if you're looking for a free alternative, you could try Algolia or Elasticsearch. Other great apps like OpenSearchServer are Apache Solr, Manticore search, Searchspring and Pagefind.