ItemsAPI is described as 'The goal of ItemsAPI is creating search application without spending time for backend. You just provide json data and your backend is ready to go'. There are more than 10 alternatives to ItemsAPI for a variety of platforms, including Mac, Windows, Linux, Online / Web-based and Self-Hosted solutions. The best alternative is Algolia. It's not free, so if you're looking for a free alternative, you could try Apache Solr or Sphinx (search engine). Other great apps like ItemsAPI are wordpress i-search pro (Paid), Elasticlunr (Free, Open Source), Expertrec Search Engine (Paid) and Apisearch (Freemium, 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 free 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.
Findberry is an internal site search service that enables web developers and site owners easily add professional, ad-free search engine to their websites so that their visitors can find content faster and easier.