Search the Invisible Web: 20 Free Resources

Expand your searches to these deep web resources

A magnifying glass, pipe, and floppy cap in reference to Sherlock Holmes

 Matt Brown / Flickr / CC BY 2.0

When you access the invisible/deep web, you're uncovering information a regular search engine won't find. This is because data on the invisible web isn't made available to software spiders and crawlers that create search engine indexes.

Given that the invisible web makes up a huge majority of the content on the web, it's fair to say that you're missing out on quite a lot if you never venture away from popular search engines like Google and Bing.

Below are 20 invisible web search engines, directories, and databases that you can use to uncover an astounding amount of content. 

The invisible web is only part of the web that common search engines don't catalog. The other portion, called the dark web, is often associated with illegal activities.

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Wayback Machine

Wayback Machine home page
What We Like
  • Lots of content.

  • Displays most pages perfectly.

  • Easy-to-understand results.

  • Keeps you on the site while browsing.

What We Don't Like
  • Keyboard shortcuts would be helpful but aren't supported.

  • Iffy keyword search.

  • Not all sites are archived.

The Wayback Machine is a deep web tool that holds a vast number of web pages, over 400 billion, in fact. As part of the nonprofit Internet Archive, the Wayback Machine has decades of web pages archived and accessible to anyone.

Not only are websites stored there but also books, audio recordings, concerts, videos, television news programs, images, and thousands of software programs.

of 20's homepage
What We Like
  • Accurately categorized results.

  • Government web pages only.

  • Ad-free.

What We Don't Like
  • Basic search is overwhelming.

  • Lacks advanced search options like filtering.

Another invisible web searcher is available at — a mammoth search engine and portal that gives you direct access to a wide variety of information and databases from the U.S. government, state governments, and local governments. includes access to the Library of Congress, an A-Z government agency index, the Smithsonian, and much more.

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The WWW Virtual Library

WWW Virtual Library's homepage
What We Like
  • Easy-to-use, simple design.

  • Curated links.

What We Don't Like
  • Many links are dead.

  • Supports only a few languages.

  • Dull user interface.

  • Pages haven't been updated since early 2017.

The WWW Virtual Library includes hundreds of different categories and databases on a wide variety of subjects, ranging from agriculture to international affairs.

The site claims that the WWW Virtual Library is the oldest catalog of the web, started by Tim Berners-Lee, the creator of HTML and of the World Wide Web itself, in 1991 at CERN in Geneva.

The website is run by volunteers who compile pages of links for particular areas in which they have expertise. The Virtual Library's deep web pages are among the highest-quality guides to specific sections of the web.

of 20's homepage
What We Like
  • Queries millions of pages.

  • Advanced search feature.

  • Lots of filtering options.

  • Results can be emailed.

What We Don't Like
  • Results seem cluttered.

  • Some search results are only contact information. searches over 60 databases and more than 2,200 selected websites from 15 federal agencies, offering 200 million pages of authoritative U.S. government science information, including research and development results. 

The website is an interagency initiative of several U.S. government science organizations. These agencies form the voluntary alliance, which governs the site.

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Wolfram Alpha

Wolfram Alpha search engine home page
What We Like
  • Covers lots of material.

  • Very detailed results.

  • Suggests searches as you type.

  • Mobile apps.

What We Don't Like
  • Not all features are free.

  • Can be overwhelming.

Wolfram Alpha is a computational deep web search engine, which means it stores a vast amount of pure data available to you by search and by a question-and-answer format.

The website aims to collect and curate all objective data; implement every known model, method, and algorithm; and make it possible to compute whatever can be computed about anything.

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The National Security Archive

National Security Archive virtual reading room
What We Like
  • Advanced search capabilities.

  • Easy-to-read synopses.

  • Thousands of documents.

What We Don't Like
  • Can't change how the results are sorted.

  • Cluttered home page could be overwhelming.

The National Security Archive at George Washington University is another free invisible web search tool that's home to a treasure trove of declassified documents, papers, and other primary-source materials on subjects related to U.S. national security, foreign policy, intelligence policy, and diplomatic and military history.

The site was founded in 1985 and is home to decades worth of documents released under the Freedom of Information Act. 

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Alexa home page
What We Like
  • Free trial.

  • Self-explanatory.

  • Lots of data.

  • Browser extension support.

What We Don't Like
  • Many tools aren't available for free.

  • No site map, search, or FAQ page.

Alexa provides analytical information about web properties that's so specific that no regular search engine can compile it. The service gathers much of its traffic data from direct sources in the form of sites that chose to install the Alexa script to certify their metrics.

The traffic estimates on Alexa are based on data from a global traffic panel, which is a sample of millions of internet users using one of thousands of different browser extensions.

Website owners especially can benefit from the data that Alexa offers; for example, here's a list of the top 500 sites on the web

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Directory of Open Access Journals

Directory of Open Access Journals' homepage
What We Like
  • All the content is free.

  • Abstract and full text.

  • Lots of filtering options.

  • Supports translations.

What We Don't Like
  • Results lack a preview.

  • Not all journals have applied and some have been removed from the site.

The Directory of Open Access Journals (DOAJ) is an invisible web resource that indexes and provides access to quality open access, peer-reviewed journals. Thousands of journals and millions of articles are searchable using the DOAJ. 

The Directory of Open Access Journals indexes research journals, periodicals, and their articles' metadata. The DOAJ aims to be comprehensive and cover all open access scientific and scholarly journals that use an appropriate quality control system. The directory's goal is to increase the visibility and ease of use of open-access scientific and scholarly journals — regardless of size and country of origin.

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The Online Books Page

The Online Books Page home page
What We Like
  • No ads.

  • Lots of ways to browse.

  • Variety of free content.

What We Don't Like
  • Bland website design.

  • Lacks advanced filtering and searching.

The Online Books Page, a deep web service offered by the University of Pennsylvania, gives readers access to more than two million books freely accessible (and readable) on the internet. Visitors also gain access to significant directories and archives of online texts, as well as special exhibits of particularly interesting classes of online books.

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The Library of Congress

The Library of Congress home page
What We Like
  • Trending searches page.

  • Lots of filtering options.

  • Search term suggestions.

  • Different viewing options.

  • Sorting capabilities.

What We Don't Like
  • Results often refer to documents only available in person.

  • All connections may be in use at peak times, interfering with search.

One of the most vivid and interactive sites on this list of invisible web resources, the Library of Congress offers an incredibly rich and varied array of content. Collection highlights include congressional records, digital preservation resources, the Veterans History Project, and the World Digital Library.

According to the site:

The Library of Congress is the nation's oldest federal cultural institution and serves as the research arm of Congress. It is also the largest library in the world, with millions of books, recordings, photographs, maps and manuscripts in its collections.
of 20 home page
What We Like
  • Helpful visuals.

  • Data finding tools and apps.

  • Variety of search term suggestions.

What We Don't Like
  • Overwhelming amount of information.

  • News and press releases mixed with data results.

If you're looking for data not found in your typical search engine, is one of the first places you'll want to visit. From geography to population statistics, you'll be able to find them on this website.

The U.S. Census Bureau conducts demographic, economic, and geographic studies and strengthens statistical development around the world through technical assistance, training, and software products.

For decades, the Census Bureau has performed international analytical work and assisted in the collection, processing, analysis, dissemination, and use of statistics with counterpart governments in over 100 countries.

of 20 home page
What We Like
  • Basic and advanced search tool.

  • Hints on how to make searches.

What We Don't Like
  • Not very user-friendly.

  • Finding the correct search option is challenging. is another U.S. government resource you can put in your invisible web search toolbox. Here, you can view works registered and documents recorded by the U.S. Copyright Office since January 1, 1978, as well as search records of registered books, music, art, periodicals, and other works, including copyright ownership documents.

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Catalog of U.S. Government Publications

Entire CGP Catalog online
What We Like
  • Updates daily.

  • Hundreds of thousands of results.

  • Manually browse pages.

What We Don't Like
  • Outdated page functions.

  • Navigation is not intuitive.

The Catalog of U.S. Government Publications gives deep web surfers instant access to electronic and print publications from the legislative, executive, and judicial branches of the U.S. government, with more than 500,000 records generated since July 1976. 

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PubMed home page
What We Like
  • Huge trove of data.

  • Data exporting capabilities.

  • Simple and advanced search options.

What We Don't Like
  • Unfriendly interface; can be hard to use.

  • Overwhelming amount of results.

PubMed, part of the National Center for Biotechnology Information, U.S. National Library of Medicine, is the perfect invisible web resource for anyone who's looking up medical or medical-related information. It offers more than 29 million citations for biomedical literature from MEDLINE, life science journals, and online books. 

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FAA Data & Research data and research page
What We Like
  • Modern interface.

  • Official, always up-to-date data.

  • Clear and understandable menu headings.

What We Don't Like
  • No advanced search options.

  • No FAQs.

The FAA Data and Research pages offer information on how FAA research is done, the resulting data and statistics, and information on funding and grant data. Anything from aviation safety to unruly passengers (seriously) can be found here. 

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DuckDuckGo search engine
What We Like
  • Privacy-conscious.

  • Forces site encryption.

  • Mobile apps.

  • Sorting and filtering options.

What We Don't Like
  • No easy-to-use advanced search box.

  • No date information in search results.

DuckDuckGo searches both the regular web and the deep web without saving any of your personal information or your search results. DuckDuckGo blocks advertising trackers to keep your search history private.

Although DuckDuckGo resembles other search engines — and a simple one at that — it's fully capable of performing advanced searches on the deep web. 

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Find legal information on the FindLaw website.
What We Like
  • Great learning resource.

  • Very comprehensive.

  • Easy to use.

  • Several filtering options.

What We Don't Like
  • Lots of ads.

  • Primarily a service referral site.

FindLaw is a gigantic repository of free legal information on the internet, and it offers one of the largest online lawyer directories available. You can use FindLaw to locate an attorney, learn more about U.S. law and legal topics, and participate in the active FindLaw community forums. 

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The Louvre

Selected Works of the Louvre-Museum
What We Like
  • Simple website.

  • A few sorting options.

What We Don't Like
  • Displays advertising.

  • Too simple of a search tool.

The online Louvre museum begs to be discovered and cherished by art lovers all over the world. View thematic collections of art, get more information about the background of selected works and view art aligned with historical events.

of 20's Indicators

Economic Indicators on
What We Like
  • Continuously updated.

  • Clear and concise data.

  • Lots of information.

  • Region-specific.

What We Don't Like
  • Poor search tool.

  • Unintuitive interface.

Economic Indicators on gives users quick access to free economic, demographic, and financial data. It provides comprehensive and extensive historical and forecasts data at the national and subnational-regional levels representing over 93 percent of global GDP.'s Indicators covers more than 180 countries, over 150 global metro areas, and all U.S. states, metro areas, and counties. The databases contain economic, financial, demographic, and consumer credit time series.

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Bankrate home page
What We Like
  • Wealth of information.

  • Extremely user-friendly.

  • Free calculators.

  • Useful sorting options.

What We Don't Like
  • Too simple of a search tool.

  • Lots of ads.

Bankrate, an online financial resource that's been around since 1996, offers a huge deep web library of financial information on current interest rates, mortgage lender reviews, ARMs, articles on CUSIP, and much more. 

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