A directory of directories is what its name implies - a website that lists web directories.
Used by webmasters and others looking for Internet directories, a directory of directories might list other directories alphabetically or it may rank them in some other manner. Like the directories themselves, listed directories may be sorted into categories, separating general directories, blog directories, forum directories, local or regional directories, or other niche directories, for the purpose of making it easier for users to find the type of directory they are looking for.
Given that a directory of directories is likely to be a much smaller directory than a general directory, it might be assembled in straight HTML, or use a blog software or some other platform, but many of them use directory scripts, such as those used by the directories they list.
The focus of this category is on directories of directories. In a sense, then, it might be considered a directory of directories of directories. Web directory review sites would also be appropriate for this category.
 
 
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Maintained by Marcus P. Zillman, executive director of the Virtual Private Library, the site represents a listing of directories, subject guides, and index resources and sites on the Internet, specifically those relating to academics and education, economics and business, government and statistics, humanities, information and information science, law, medicine, news, science and engineering, and social sciences. Only titles and URLs are included.
http://www.2019directoryofdirectories.com/
Confused as to which directories are the best to submit your site to? Objectively determining the best directories is difficult without a metric. Since Google quit publishing its Page Rank, Moz developed a method of determining domain strength, which predicts a domain’s ranking potential in the search engines. Listed here are the strongest directories, ranked from the highest in Domain Authority, as well as the basic and featured submission prices for each.
http://www.avivadirectory.com/strongest-directories/
Featuring lists, and links to free, paid, regional and niche web directories, arranged into categories, the directory also offers up-to-date rankings and reviews significant directories on the Internet. Other topics include submission tips and suggestions aimed at increasing the chances of a successful web directory submission campaign, including tips on selecting the right paid directory, as well as a glossary of directory SEO terminology.
http://www.best-web-directories.com/
Directory Critic lists search engine friendly web and article directories that webmasters may use as site promotion tools. The top five ranked website directories, according to reader votes, are featured on the index page, and separate lists of free directories, paid directories, niche directories, article directories, and directories that accept deep links. A blog is included, and advertising opportunities are available. Directory Critic also operates a submission service.
http://www.directorycritic.com/
The directory features a collection of topic-specific (niche) directories covering a wide variety of categories, including article directories, arts and crafts, blogging, business, electronics, financial, gaming, health, home and gardens, and shopping, as well as directory lists, regional directories, and webmaster directories. A brief description is included for each, along with a separate page with additional details, including listing dates and Alexa traffic rank.
http://www.ewebpages.org/Computers/Internet/Web-Directories/Niche/
Jasmine Directory - Best Web Directories
Robert Gombos, of the Jasmine Directory, discusses several of the characteristics of a high-trust directory, lists some sources of additional information that can be used in choosing a directory, and includes a comparison between some of the best web directories, using a variety of metrics, lists of directories that comply with Google’s terms of service (TOS), tips for saving webmasters time and money while engaging in a web directory submission campaign.
https://www.jasminedirectory.com/best-web-directories.html
With a focus on web directories that require a submission fee, the directory of directories highlights the ten directories that it considers to be at the top, and categorizes other listed directories into various categories, including those that accept or include deep links, those with a high page rank, those with strong backlinks, and those that offer free submission options. Paid directories that are not already listed may be submitted, with payment of a fee.
http://www.paiddirectories.info/
Online since 1998, the directory lists hundreds of search engines, organized by country and by topic. Web directories are also listed if the include a searchable database. The directory contains thousands of listings from more than three hundred countries and territories, categorized by nation, country, or autonomous government. Within the category, each directory or search engine is listed alphabetically, although priority placement opportunities are available.
http://www.searchenginecolossus.com/
Web Directory List features a highly promoted, well organized, and useful resource that lists high-quality web directories and directory-related sites, sorted by bid amount. The top ten directories are listed on the homepage and the top twenty on the top links page for greater exposure. Separate lists for the top free directories, the top paid directories, top article directories, top business directories, and blog directories are included, along with informational articles.
http://www.webdirectorylist.com/