It is the most-used search engine on the World Wide Web, handling more than three billion searches each day. As of February 2016, it is the most used search engine in the US with 64.0% market share. The main purpose of Google Search is to hunt for text in publicly accessible documents offered by web servers, as opposed to other data, such as images or data contained in databases. It was originally developed by Larry Page and Sergey Brin in 1997. Google Search provides several features beyond searching for words. These include synonyms, weather forecasts, time zones, stock quotes, maps, earthquake data, movie shows, airports, home listings, and sports scores.

Bing is a web search engine owned and operated by Microsoft. The service has its origins in Microsoft’s previous search engines: MSN Search, Windows Live Search and later Live Search. Bing provides a variety of search services, including web, video, image and map search products. As of November 2015, Bing is the second largest search engine in the US, with a query volume of 20.9%, behind Google on 63.9%. Yahoo! Search, which Bing largely powers, has 12.5%. Bing includes many features includes the interface, media, instant answers, local info, third-party integration, integration with Windows 8, translator, and international multilingual coverage.

Yahoo! Search is a web search engine owned by Yahoo, It is the third largest search engine in the US by the query volume at 12.8%, after its competitors Google at 64.5% and Bing at 19.8%. Yahoo Search also provided their search interface in at least 38 international markets and a variety of available languages. Yahoo! has a presence in Europe, Asia and across the Emerging Markets. Yahoo Search indexed and cached the common HTML page formats, as well as several of the more popular file-types, such as PDF, Excel spreadsheets, PowerPoint, Word documents, RSS/XML and plain text files.

Baidu, Inc. incorporated on 18 January 2000, is a Chinese web search engine. It is one of the largest internet companies, and one of the premiers AI leaders in the world. Baidu offers several services to locate information, products and services using Chinese-language search terms, such as, search by Chinese phonetics, advanced search, snapshots, spell checker, stock quotes, news, knows, post bar, images, video and space information, and weather, train and flight schedules and other local information. The user-agent string of Baidu search engine is Baiduspider. Also, a Baidu application for Apple’s iOS is available.

DuckDuckGo is an Internet search engine that emphasizes protecting searchers’ privacy and avoiding the filter bubble of personalized search results. DuckDuckGo distinguishes itself from other search engines by not profiling its users and by deliberately showing all users the same search results for a given search term. DuckDuckGo’s results are a compilation of “over 400” sources, including Yahoo! Search BOSS; Wikipedia; Wolfram Alpha; Bing; its own Web crawler (the DuckDuckBot); and others. It also uses data from crowdsourced sites, including Wikipedia, to populate “Zero-click Info” boxes – grey boxes above the results that display topic summaries and related topics.

EXALEAD is a software company, created in 2000, that provided search platforms and search-based applications(SBA) for consumer and business users. The company is headquartered in Paris, France, and is a subsidiary of Dassault Systèmes. Exalead has been called “Google on Steroids” and the “French Google.” According to an article from TechCrunch Europe, the Exalead company was founded in 2000 in France, and it was acquired by Dassault Systemes in June 2010.  Through the free search platform on the Exalead website, users can search for web results, images, videos, and Wikipedia articles.  An Exalead Desktop feature for searching through personal files is also available.

Munax is an all-content search engine and powered nationwide and worldwide public search engines with a page, document, audio, video, images, software, and email search. Munax can be installed on a single computer or an arbitrary number of computers on a local area network, or over computers on the internet. Munax provided a long range of search features, including the search for pages, documents, audio, video, images, compressed files, torrents, software and email addresses, or to get all type of results on the same page (composite search, super search).

Qwant search engine processes well over 10 million search requests per day, spread over its three main entry points: the normal homepage, a ‘lite’ version which mimics Google’s homepage, and a ‘Qwant Junior’ portal for children that filters results. In March 2017, press articles suggest that Qwant search results are mainly based on Bing search results, except in France and Germany. Qwant also confirmed the use of Bing advertising network. Qwant offers several ways to filter results to areas of interest: Web, Images, News, Social, Shopping.

Sogou search engine (Sogou.com) was launched on 3 August 2004, and is currently the third-largest search engine in China. Sogou’s web application products are designed to classify online information, such as music, picture, video clip, news, map and vertical information.

Soso was a Chinese search engine owned by Tencent Holdings Limited, which is well known for its other creations Pengyouand QQ. As of 1 October 2012, Soso was ranked as the 33rd most visited website in the world, the 11th most visited website in China, and the number eight most visited website in South Korea, according to Alexa Internet.

Yandex Search is a web search engine owned by Russian corporation Yandex. It is the core product of Yandex. In January 2015 Yandex Search generated 51.2% of all search traffic in Russia according to Liveinternet.The search technology provides local search results in more than 1,400 cities. Yandex Search also features “parallel” search that presents results from both main web index and specialized information resources, including news, shopping, blogs, images and videos on a single page. Yandex Search is responsive to real-time queries, recognizing when a query requires the most current information, such as breaking news or the most recent post on Twitter on a particular topic.

Youdao is a search engine released by Chinese internet company NetEase in 2007. It is the featured search engine of its parent company’s web portal, 163.com, and lets users search for web pages, images, news, music, blogs, Chinese-to-English dictionary entries, and more.

Ask.com (originally known as Ask Jeeves) is a question answering-focused e-business and web search engine founded in 1996 In 2010, Ask.com abandoned the search industry because it could not compete against more popular search engines such as Google. Earlier in the year, Ask had launched a Q&A community for generating answers from real people as opposed to searching algorithms then combined this with its question-and-answer repository, utilizing its extensive history of archived query data to search sites that provide answers to questions people have.

AOL Search provides users with access to the web, image, multimedia, shopping, news and local search results. By default, a search on AOL Search brings back matches from across the web. Most of these web listings come from Google, but listings from other data sources may also appear. For popular queries (such as cars), AOL may present a “Snapshot” area at the top of the page containing listings selected by its own editors, AOL-owned material or sponsored listings. There is no way to submit to AOL editors for inclusion here.

Alexa provides web traffic data, global rankings, and other information on 30 million websites. As of 2015, its website has been visited by over 6.5 million people monthly. Visitors to the Alexa website can: see data for Alexa Top Sites, search to see traffic data, such as ranking and bounce rate, for websites that aren’t included in the top-ranked sites, download the Alexa toolbar, which  allows them to see statistics for websites as they browse and records their browsing data for inclusion in Alexa statistics, and create a custom toolbar, which can be shared.

Ciao is a European-based online-shopping portal with websites in the United Kingdom, France, Spain, Germany, the Netherlands, Italy and Sweden. The site provides a forum where registered users can write reviews and give their opinions on a wide variety of products to help others make decisions. As well as offering reviews, the site also provides price comparison (working with merchants and agencies who provide data feeds) and allows the user to click through and purchase products. Ciao claims that it reaches an audience of 28.4 million monthly unique visitors in Europe.

Lycos, Inc., is a web search engine and web portal established in 1994, spun out of Carnegie Mellon University. Lycos also encompasses a network of email, web hosting, social networking, and entertainment websites. Lycos web search results come from LookSmart or AllTheWeb. LookSmart directory listings are likely to appear for popular, commercially oriented queries. After any LookSmart listings, or in place of them for more specific queries, listings from AllTheWeb are shown.

IFACnet, the KnowledgeNet for Professional Accountants, is the global, multilingual search engine developed by the International Federation of Accountants (IFAC) and its members to provide professional accountants worldwide with one-stop access to good practice guidance, articles, management tools and other resources. This enterprise search engine was launched on October 2, 2006, by INDEZ. Originally marketed to professional accountants in business, IFACnet was expanded in March 2007 to provide resources and information relevant to small and medium accounting practices. It now includes resources and information for accountants in all sectors of the profession.

Business.com is a digital media company and B2B web destination which offers various performance marketing advertising, including lead generation products on a pay per lead and pay per click basis, directory listings and display advertising. The site covers business industry news and trends for growth companies and the B2B community to stay up-to-date, currently housing more than 15,000 pieces of content as of November 2014. In October 2014, the website was ranked #1 on Inc.com’s ’50 Websites Your Startup Needs to Succeed’.

LexisNexis Group is a corporation providing computer-assisted legal research as well as business research and risk management services. As of 2006, the company has the world’s largest electronic database for legal and public-records related information.

Majestic is a type of web search engine derived from a distributed web crawler (or bot) called MJ12Bot. Majestic maps the links between web pages, rather than the web content itself. This network of links is sometimes called the web graph. The Majestic Search Engine’s data is accessible through APIs in JSON and XMLformats or via a web interface.

ThomasNet.com is the leading product sourcing and supplier discovery platform for procurement professionals, engineers, plant & facility management and business owners seeking trusted suppliers for MRO, OEM and other products/services for their industrial, manufacturing, commercial and institutional businesses. ThomasNet listings contain information on each company, including their size, amount of annual sales, history, product information, and so on. From a company’s ThomasNet listing, a lead can send an email, request a quote, or visit the company’s website.

Alibaba.com, the primary company of Alibaba, is as of 2014, the world’s largest online business-to-business trading platform for small businesses. Founded in Hangzhou in eastern China, Alibaba.com has three main services. The company’s English language portal Alibaba.com handles sales between importers and exporters from more than 240 countries and regions. The Chinese portal 1688.com was developed for domestic business-to-business trade in China. In addition, Alibaba.com offers a transaction-based retail website, AliExpress.com, which allows smaller buyers to buy small quantities of goods at wholesale prices.

Kompass is one of the world’s leading Business-to-Business information provider and is now present in more than 60 countries. For over 70 years, the global business community has relied on Kompass for quality information and for exposure in the international marketplace. It is considered as an effective marketing tool to help your business find businesses globally. Kompass can help your business to promote to the global marketplace, analyze Global market sectors for potential opportunities, identify suppliers of products & services, identify potential clients, agents, and distributors, identify potential partners, identify and research competitors.

Shodan is a search engine that lets the user find specific types of computers (webcams, routers, servers, etc.) connected to the internet using a variety of filters. Some have also described it as a search engine of service banners. Unlike Google, which crawls the Web looking for websites, Shodan navigates the Internet’s back channels. It’s a kind of “dark” Google, looking for the servers, webcams, printers, routers and all the other stuff that is connected to and makes up the Internet. Shodan runs 24/7 and collects information on about 500 million connected devices and services each month.

BTDigg was the first BitTorrent DHT search engine. It participated in the BitTorrent DHT network, supporting the network and making correspondence between magnet links and a few torrent attributes (name, size, list of files) which are indexed and inserted into a database. For end users, BTDigg provides a full-text database search via Web interface. The web part of its search system retrieved proper information by a user’s text query. The Web search supported queries in European and Asian languages.

Isohunt is a BitTorrent search site. Isohunt does not host BitTorrent files, Isohunt only helps you find BitTorrent files. IsoHunt crawls several different torrent sites, and when searchers look for torrents here, they get links to sites where the .torrent files can be found. If you search for BitTorrents on Isohunt, you’re searching for links to torrent files found elsewhere on the Web.

On April 4th, 2017 Mininova.org was shut down. Mininova was a website offering BitTorrent downloads. Mininova was once one of the largest sites offering torrents of copyrighted material, but in November 2009, following legal action in the Dutch courts, the site operators deleted all torrent files uploaded by regular users including torrents that enabled users to download copyrighted material.

The Pirate Bay (sometimes abbreviated to TPB) is an online index of digital content of entertainment media and software. Founded in 2003 by Swedish, The Pirate Bay allows visitors to search, download and contribute magnet links and torrent files, which facilitate peer-to-peer file sharing among users of the BitTorrent protocol. The Pirate Bay available in 35 languages and primarily in English and Swedish. The revenue of The Pirate Bay comes from Advertisements, donations, and merchandise.

TorrentSpy was a popular BitTorrent indexing website. It provided .torrent files, which enabled users to exchange data between one another. It also provided a forum to comment on them and integrated the user-driven content site ShoutWire into the front page. In August 2007, there were more than 1,000,000 torrents indexed with thousands of new torrents indexed every day. On March 24, 2008, TorrentSpy shut itself down.

Torrentz.eu, one of the most popular torrent meta-search engine bids farewell as it has been shut down. The actual reason for the shutdown is still unknown and has come as a surprise to all torrent lovers. Torrentz had millions of visitors per day and with this shutdown, the 13-year long service has come to an end. The website (and its mirrors) are still up and running but the no one can access its database and search any torrent file on Torrentz.

Chegg is an American online textbook rental company, that specializes in online textbook rentals on both in physical and digital formats, homework help, online tutoring, scholarships and internship matching. It is meant to help students in high school and college. It also owns citation services EasyBib, Citation Machine, BibMe, and Cite This For Me. The company was created in the United States by three Iowa State University students in 2001.

Noodle, based in New York, NY, is a company that helps students make decisions about education. Noodle provides expert advice and comprehensive data on more than 700,000 education providers and resources, including preschools, K-12 schools, colleges, graduate programs, tutors, and learning materials. “Noodle is the first of its kind to focus specifically on aggregating information for students and families looking for information on anything from tutors to summer camps to master’s programs.

BASE surpassed the 100 million documents threshold having indexed 100,183,705 documents from 4,695 content sources. BASE users can search bibliographic metadata including abstracts, if available. However, BASE does not currently offer full-text search. It contrasts with commercial search engines in multiple ways, including in the types and kinds of resources it searches and the information it offers about the results it finds. Results can be narrowed down using drill-down menus (faceted search). Bibliographic data is provided in several formats, and the results may be sorted by multiple fields, such as by author or year of publication.

CiteULike is a web service which allows users to save and share citations to academic papers. Based on the principle of social bookmarking, the site works to promote and to develop the sharing of scientific references amongst researchers. In the same way that it is possible to catalog web pages (with Furl and delicious) or photographs (with Flickr), scientists can share citation information using CiteULike.

Google Scholar is a freely accessible web search engine that indexes the full text or metadata of scholarly literature across an array of publishing formats and disciplines. Released in beta in November 2004, the Google Scholar index includes most peer-reviewed online academic journals and books, conference papers, theses and dissertations, preprints, abstracts, technical reports, and other scholarly literature, including court opinions and patents.

The Library of Congress search engine is the largest library search engine in the world, with millions of books, recordings, photographs, newspapers, maps and manuscripts in its collections. The Library of Congress search engine preserves and provides access to a rich, diverse and enduring source of knowledge to inform, inspire and engage you in your intellectual and creative endeavors.

Cappex is the education search engine to find the colleges based on users options. It’s the place to discover new colleges and scholarships, compare your top choices and make the decisions that give you peace of mind.

Funnelback is a search engine platform. Funnelback is typically deployed as a vertical search (site search) or enterprise search solution and has been cited as suitable for search-based applications. It features a broad array of plug-ins and APIs and is platform-agnostic.

Q-Sensei is a search-based application for searching through unstructured and structured data. Q-Sensei makes searching through diverse types and sources of data faster, easier, and more powerful. Q-Sensei is based on multi-dimensional search, which combines full text with faceted search and content analysis to present data organized and correlated along multiple facets or “dimensions” (e.g. date, tag, author, source, language, content type, etc.). This lets the end user dive deeper into a search query on multiple fronts.

The TeraText suite of products includes a number of technologies for solving complex archival, search, and text-oriented problems. These include an enterprise-class email and attachments search platform, a high- performance repository for text-rich assets, and document management and metadata publishing systems.

SimilarWeb uses data extracted from four main sources: 1. A panel of web surfers made of millions of anonymous users equipped with a portfolio of apps, browser plugins, desktop extensions and software; 2. Global and Local ISPs and data partnerships; 3. Web traffic directly measured from a learning set of selected websites and apps intended for specialized estimation algorithms; 4. A colony of web crawlers that scan the entire Web and apps stores.

Swiftype provides enterprise search and searches engine platforms for organizations, websites, and applications. In 2017, Swiftype was acquired by Elastic, the makers of Elasticsearch.

dtSearch developer products provide efficient multithreaded searching, with no limit on the number of concurrent search threads. For the online search, the products can run in a completely stateless manner, making it very easy to scale. Intel describes dtSearch’s “perfect score” for high-volume web-based concurrent searching.

The Google Search Appliance was a rack-mounted device that provided document indexing functionality. The operating system is based on CentOS. The Google Search Appliance contains Google search technologies and a means of configuring and customizing the appliance.

Northern Light is specializing in strategic research portals, enterprise search technology, and text analytics solutions. Northern Light operated a Web search engine for public use. It was regarded at the time as innovative in the provision of search based on classification and inclusion of both public and proprietary information resources. During this time period, Northern Light also developed private custom search engines for large corporate clients marketed under the trade name SinglePoint.

OpenText Search is built on the foundation of a robust, scalable, Enterprise Content Management (ECM) platform. It provides unified access to multiple internal and external information sources from a single interface, which enables users to easily locate and access content, regardless of file type, format, or location. One of the main benefits OpenText Search offers is the relevancy of results that are consistently delivered to improve your organization’s competitive advantage and provide a satisfying end-user experience.

Yippy is a metasearch engine developed by Vivísimo before Vivisimo was later acquired by IBM and renamed IBM Watson Explorer which offers clusters of results. Seem to be powered by Bing.

RecipeBridge.com is a vertical search engine for recipes, allowing people to find recipes on thousands of cooking sites and recipe blogs. After years of searching through Google results for recipes, RecipeBridge decided that cooks around the world deserved a simple way to find any recipe. RecipeBridge was founded in 2009 to reinvent and simplify the way that cooks using the Internet find quality recipes. RecipeBridge currently indexes over 1.8 million recipes from over 300 sites.

Yummly is a mobile app and website that provides recipe recommendations personalized to the individual’s tastes, semantic recipe search, a digital recipe box, shopping list and one-hour grocery delivery. The Yummly app is available for iOS, Android and web browsers. Yummly uses patent-pending technology, and a hand-curated knowledge graph to offer a semantic web search engine for food, cooking, and recipes. Yummly allows users to search by ingredient, diet, allergy, nutrition, price, cuisine, time, taste, meal courses and sources; and ‘learns’ about users based on their likes and dislikes. Yummly uses this information to categorize food for search and make recommendations.

LinkedIn is a business and employment-oriented social networking service that operates via websites and mobile apps. Founded on December 28, 2002, and launched on May 5, 2003. It is mainly used for professional networking, including employers posting jobs and job seekers posting their CVs. As of 2015, most of the company’s revenue came from selling access to information about its members.

Macavo.com is a family history search engine, Mocavo established itself very quickly as one to watch in the world of genealogy. In June 2011, just three months after launch, Family Tree Magazine named Mocavo as one of the best 101 genealogy websites of the year. This growth continued, as Mocavo launched a Free Yearbook Collection and worked with users to publish hundreds of new records and archives every day.

FindFace is a website that lets users search for members of the social network VK by uploading a photograph. FindFace employs a facial recognition neural network algorithm developed by N-Tech.Lab to match faces in the photographs uploaded by its users against faces in photographs published on VK, with a reported accuracy of 70 percent.

InfoSpace is a leading provider of white label search and monetization solutions. InfoSpace serves a network of more than 100 web publishers globally, offering core search solutions as a proven means to monetize audience via a search-based advertising revenue stream.

PeekYou is a people search engine that indexes people and their links on the web. PeekYou claims to have indexed over 250 million people, mostly in the US and Canada. The search results are built from publicly available URLs, including Facebook, LinkedIn, Wikipedia, Google+, blogs, homepages, business pages and news sources.

Spock is a vertical search engine or entity search engine on people. Spock has “indexed over 250 million people representing over 1.5 billion data records.” These records are from publicly available sources, including Wikipedia, IMDB, ESPN, LinkedIn, Hi5, MySpace, Friendster, Facebook, YouTube, Flickr, Twitter, corporate biographies, university faculty and staff pages, real estate agents sites, school alumni and member directory pages, etc. The company maintains that “30% of all Internet searches are people-related”.

Spokeo is a people search website that aggregates data from online and offline sources. Spokeo has evolved to become an information-gathering website that offers various options for finding information about people. It purports to know, among other things, one’s income, religion, spouse’s name, credit status, the number of people in the household, a satellite shot of the house and its estimated value.

Zabasearch is a useful search tool that focuses on finding only data related to individual people (names, addresses, phone numbers). You can use Zabasearch as a tool when you’re trying to find someone online, or simply as a way to verify an address. All of the data found using Zabasearch is collected using publicly available data feeds.

ZoomInfo is a free service that’s gathered information about more than 25 million people—including you if you have even a minimal presence on the web. ZoomInfo was created specifically to help searchers locate accurate, reliable information about people. The service crawls the web much like others search engine but focuses on information about people. Using a combination of artificial intelligence and natural language techniques, ZoomInfo connects information about individuals from disparate sources and gradually builds up online resumes that include employment information, educational background, and other details.

Adzuna is a search engine for job advertisements. Adzuna search thousands of websites so you don’t have to and bring together millions of ads so you can find every job, everywhere, via Adzuna. Adzuna provides smarter search options and powerful data about the job market, giving you the information you need to take control of your career.