Specialized search engines vary greatly from one to the other, in both size and scope. They also cover a variety of topics including medicine, science, automobiles, sports, education, and travel. This is one of the oldest guides, listing over 2,500 specialized search engines, directories, and indexes, divided into 15 subject categories and over 40 subcategories. Beaucoup includes both academic and general engines in the sciences, technology, politics, government, and the humanities. This guide lists over 1,500 specialized search engines divided into 19 main categories and hundreds of subcategories.
Coverage is broad and includes topics for general, professional, and academic audiences.
Subjects include computers, education, health, and law. This site contains over 10,000 search engines divided into 18 subject categories and hundreds of subcategories. Subjects include investments, legal, travel, sciences, and reference materials. This site is divided into 14 subject categories and further divided into many subcategories. This site is a geographical guide to search engines.