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.
DuckDuckGo - The Internet privacy company that empowers you to seamlessly take control of your personal information online, without any tradeoffs.
Google Custom Search - Google Custom Search enables you to create a search engine for your website, your blog, or a collection of websites.
Google - Google Search, also referred to as Google Web Search or simply Google, is a web search engine developed by Google. It is the most used search engine on the World Wide Web
ElasticSearch - Elasticsearch is an open source, distributed, RESTful search engine.
Searx - Open source metasearch engine