Apisearch is described as 'Search over millions of documents, and give to your users unique, amazing and unforgettable experiences' and is a Search Server in the Online Services category. There are more than 25 alternatives to Apisearch for a variety of platforms, including Online / Web-based, Linux, Windows, Mac and Self-Hosted solutions. The best alternative is elasticsearch, which is free. Other great apps like Apisearch are Algolia (Free Personal), Apache Solr (Free, Open Source), Sphinx (search engine) (Free) and Manticore search (Free, Open Source).
Solr is an open source enterprise search server based on Lucene search library, with XML/HTTP and JSON APIs. Its major features include powerful full-text search, hit highlighting, faceted search, dynamic clustering, database integration, and rich document handling.
Sphinx is a software search engine designed with indexing database content in mind. It currently supports MySQL, PostgreSQL, and ODBC-compliant databases as data sources natively. Other data sources can be indexed via pipe in a custom XML format.
Azure Search makes it easy to add powerful and sophisticated search capabilities to your website or application. Quickly and easily tune search results and construct rich, fine-tuned ranking models to tie search results to business goals.