Azure Cognitive Search - Azure Search makes it easy to add powerful and sophisticated search capabilities to your website or...
Site Search 360 - Site Search 360 enhances and improves your built-in CMS or product search with autocompletion, semantic search, filters, facets, detailed analytics, and a whole lot of customization options.
Algolia - Algolia's Search API makes it easy to deliver a great search experience in your apps & websites. Algolia Search provides hosted full-text, numerical, faceted and geolocalized search.
ElasticSearch - Elasticsearch is an open source, distributed, RESTful search engine.
Carrot2 - Carrot2 organizes your search results into topics. With an instant overview of what's available, you will quickly find what you're looking for.
Google Custom Search - Google Custom Search enables you to create a search engine for your website, your blog, or a collection of websites.