10 Search Engines to Explore the Invisible Web

maze   10 Search Engines to Explore the Invisible WebNo, it’s not Spiderman’s latest web slinging tool but something that’s more real world. Like the World Wide Web.

The Invisible Web refers to the part of the WWW that’s not indexed by the search engines. Most of us think that that search powerhouses like Google and Bing are like the Great Oracle”¦they see everything. Unfortunately, they can’t because they aren’t divine at all; they are just web spiders who index pages by following one hyperlink after the other.

But there are some places where a spider cannot enter. Take library databases which need a password for access. Or even pages that belong to private networks of organizations. Dynamically generated web pages in response to a query are often left un-indexed by search engine spiders.

Search engine technology has progressed by leaps and bounds. Today, we have real time search and the capability to index Flash based and PDF content. Even then, there remain large swathes of the web which a general search engine cannot penetrate. The term, Deep Net, Deep Web or Invisible Web lingers on.

To get a more precise idea of the nature of this “˜Dark Continent’ involving the invisible and web search engines, read what Wikipedia has to say about the Deep Web. The figures are attention grabbers ““ the size of the open web is 167 terabytes. The Invisible Web is estimated at 91,000 terabytes. Check this out – the Library of Congress, in 1997, was figured to have close to 3,000 terabytes!

How do we get to this mother load of information?

That’s what this post is all about. Let’s get to know a few resources which will be our deep diving vessel for the Invisible Web. Some of these are invisible web search engines with specifically indexed information.


Search Engine01   10 Search Engines to Explore the Invisible Web

Infomine has been built by a pool of libraries in the United States. Some of them are University of California, Wake Forest University, California State University, and the University of Detroit. Infomine “˜mines’ information from databases, electronic journals, electronic books, bulletin boards, mailing lists, online library card catalogs, articles, directories of researchers, and many other resources.

You can search by subject category and further tweak your search using the search options. Infomine is not only a standalone search engine for the Deep Web but also a staging point for a lot of other reference information. Check out its Other Search Tools and General Reference links at the bottom.

The WWW Virtual Library

Search Engine02   10 Search Engines to Explore the Invisible Web

This is considered to be the oldest catalog on the web and was started by started by Tim Berners-Lee, the creator of the web. So, isn’t it strange that it finds a place in the list of Invisible Web resources? Maybe, but the WWW Virtual Library lists quite a lot of relevant resources on quite a lot of subjects. You can go vertically into the categories or use the search bar. The screenshot shows the alphabetical arrangement of subjects covered at the site.


Search Engine03   10 Search Engines to Explore the Invisible Web

Intute is UK centric, but it has some of the most esteemed universities of the region providing the resources for study and research. You can browse by subject or do a keyword search for academic topics like agriculture to veterinary medicine. The online service has subject specialists who review and index other websites that cater to the topics for study and research.

Intute also provides free of cost over 60 free online tutorials to learn effective internet research skills. Tutorials are step by step guides and are arranged around specific subjects.

Complete Planet

Search Engine04   10 Search Engines to Explore the Invisible Web

Complete Planet calls itself the “˜front door to the Deep Web’. This free and well designed directory resource makes it easy to access the mass of dynamic databases that are cloaked from a general purpose search. The databases indexed by Complete Planet number around 70,000 and range from Agriculture to Weather. Also thrown in are databases like Food & Drink and Military.

For a really effective Deep Web search, try out the Advanced Search options where among other things, you can set a date range.


Search Engine05   10 Search Engines to Explore the Invisible Web

Infoplease is an information portal with a host of features. Using the site, you can tap into a good number of encyclopedias, almanacs, an atlas, and biographies. Infoplease also has a few nice offshoots like Factmonster.com for kids and Biosearch, a search engine just for biographies.


Search Engine06   10 Search Engines to Explore the Invisible Web

DeepPeep aims to enter the Invisible Web through forms that query databases and web services for information. Typed queries open up dynamic but short lived results which cannot be indexed by normal search engines. By indexing databases, DeepPeep hopes to track 45,000 forms across 7 domains.

The domains covered by DeepPeep (Beta) are Auto, Airfare, Biology, Book, Hotel, Job, and Rental. Being a beta service, there are occasional glitches as some results don’t load in the browser.


Search Engine07   10 Search Engines to Explore the Invisible Web

IncyWincy is an Invisible Web search engine and it behaves as a meta-search engine by tapping into other search engines and filtering the results. It searches the web, directory, forms, and images. With a free registration, you can track search results with alerts.


Search Engine08   10 Search Engines to Explore the Invisible Web

DeepWebTech gives you five search engines (and browser plugins) for specific topics. The search engines cover science, medicine, and business. Using these topic specific search engines, you can query the underlying databases in the Deep Web.


Search Engine09   10 Search Engines to Explore the Invisible Web

Scirus has a pure scientific focus. It is a far reaching research engine that can scour journals, scientists’ homepages, courseware, pre-print server material, patents and institutional intranets.


Search Engine10   10 Search Engines to Explore the Invisible Web

TechXtra concentrates on engineering, mathematics and computing. It gives you industry news, job announcements, technical reports, technical data, full text eprints, teaching and learning resources along with articles and relevant website information.

Just like general web search, searching the Invisible Web is also about looking for the needle in the haystack. Only here, the haystack is much bigger. The Invisible Web is definitely not for the casual searcher. It is a deep but not dark because if you know what you are searching for, enlightenment is a few keywords away.

Do you venture into the Invisible Web? Which is your preferred search tool?

Image credit: MarcelGermain

The comments were closed because the article is more than 180 days old.

If you have any questions related to what's mentioned in the article or need help with any computer issue, ask it on MakeUseOf Answers—We and our community will be more than happy to help.



Good info. Thanks,


Thanks, glad you liked it:)

Herrnan Valdes

Thank you….will pass it on to my contacts.

Marcus Zillman

Resources for Deep Web Research


Thanks for this.

Rodddy MacLeod

Good list of tools which will help undergraduates.

Here’s some more: 10 interesting websites #4 http://roddymacleod.wordpress….

David Rogers

Saikat, thanks. I´ve bookmarked most of these sites plus your article, in a Deep Search folder. One of the helpful items in your article directs me to a guide for learning how to search better. That´s where I´m going first. Later, when I have a topic I want to search in depth, I´ll be prepared for the hunt, thanks to you.

Rodddy MacLeod

Good list of tools which will help undergraduates.

Here’s some more: 10 interesting websites #4 http://roddymacleod.wordpress.com/2010/03/11/10-interesting-websites-4-as-selected-by-roddy-macleod/


Beautiful…………thats like openning a few more libraries.


Great article!!
Thank You Very VERY Much.


Thank you, thank you:) I’m constantly looking for more research resources for the subjects I’m researching.


This is an excellent information find that I look forward to putting to use. I’m much more of a grandmother than a geek, but do use the internet to research things of interest to me & my family.
I was surprised to find, when I checked it in print preview, that the first 2 pages of 7 for this article don’t set up right to be printed off, which is what I was going to do (told you I’m not a Geek).
Anyway, I’m pleased to have found this article & site.


I tested out this post in Firefox and yes, it did not give a great preview of the print. But if you have Internet Explorer installed, then the Print Preview in that comes out okay.

I am glad you liked the post. One of our basic purpose is to focus on technology that an everyman (or woman) can use. Do keep visiting.


It would be nice to see any documented research comparing the search results and their usefulness from the open web search engines and the invisible web search engines. In other words, how do I know that the results I’m getting on a certain subject with these 10 are better/more useful than what google/yahoo/bing/etc… would provide? I can and will test some of it myself, but as I said, it would be nice to see some good objective research…

Rodddy MacLeod

Excellent idea to actually do some research and compare these tools.

dave tribbett

Great post.
http://tastethecloud.com/conte… is a good article that adds some additional detail to the topic and a good set of links to the deep web search engines and other helpful sites.


Great info, one quibble-it’s mother “lode” not “load”. Term comes from mining.


You are doing simply fantastic job I love this site and hearty congrats a great job you are doing thanks for every thing

Rodddy MacLeod

Those 10 search engines are popular with information professionals.

Here’s another one that lets you can search the latest Table of Contents (TOCs) of 13,325 journals collected from 433 publishers (searching 348,158 TOC articles). http://www.journaltocs.hw.ac.u


Concise yet informative article. Great job. Keep it up.

Rodddy MacLeod

Those 10 search engines are popular with information professionals.

Here’s another one that lets you can search the latest Table of Contents (TOCs) of 13,325 journals collected from 433 publishers (searching 348,158 TOC articles). http://www.journaltocs.hw.ac.uk/


Useful info. However, “Complete Planet” doesn’t seem to have been updated since March 5th, 2004, and the date range search didn’t work for me.


The site is apparently being ‘re-engineered‘ and the new one will be reopened in late 2010.


None of these web engines are useful to me, because I couldn’t find an e-book or lecture of Design and analysis Of Algorithms By Annany Levitin.


Thanks for the post! I wish there was a usable tech search site. I remember a time when you could type in a serial or model number into Poople and get diagrams, setup info . . sigh . . . now all you get is pure crap or $$$$$ sites.

Here is one started by CMU sometime ago. Seemingly, it also is bent towards academics . . sigh . . where are the useful TECH search sites!?!?!?!

Anyway, here’s CMU’s work on deep web.



Hmmm…that’s true. Let me work on that and see if I can come up with something.

pedro parkero

Yeah, I have the same wish as dale… just these past hour I wondered what are the chances of me finding a service manual to an MSI notebook I have to replace an internal DVD drive of, and so far, my search has gone dry…
I guess it’s too much to hope that it’s in the Internet, huh… :-/


Same as Dale – Tech search for diagrams etc related to m/s number etc for products would be ftw :)

Rodddy MacLeod


See my post: Ten science search engines

Rodddy MacLeod

Also of possible interest is: 10 websites to help you keep up-to-date with scholarly journal contents http://hwlibrary.wordpress.com/2009/10/21/10-websites-to-help-you-keep-up-to-date-with-scholarly-journal-contents/


Test these against a known search. A search that I do almost daily turns up 4,000 results on Google.
Infomine: Your search could not be processed due to an error.
WWW Virtual Library: no results


This will surely prove very useful.Thanks..

John Cook

Some time ago, for a friend, I produced an exceptionally realistic drawing of a stack of three future DVX’s titled “The New York Library” and each was proclaimed to be 2000TB. While no intention to mock reality was intended, it is a bit shocking to see that other than the over capacity DVD’s this could be considered current and accurate.

I for one would love to see ALL the available information, but categorized into sections. Start with science fact, then literature that is considered accurate. . . and somewhere near the end would be current religious beleifs.


We don’t know what we already know. Networking is essential in key words, and intuition. So we can rearange the natural fractal ordination basicaly there is in this world our Universe.
Let there be a insite contact with God- inner self to make the right ordination and to see; chaos is just a moment that only we don’t see the ordination wich is always and already there !

Rodddy MacLeod

JournalTOCs is now the biggest, free and searchable collection of scholarly journal Tables of Contents (TOCs) http://www.journaltocs.hw.ac.u


Thanks for the information
Keep up the Good work


Nice post. How about the Real Time Social Search Engines like Topsy Tweet Search and Buzzom People search?

Joe Gumshoe

I suspect the numbers earlier in the article might be off a bit. I can’t say for sure of course, but I suspect the open web is far more than 167 TB. If you consider the video content I would bet that YouTube alone exceeds that.

I do definitely appreciate the article, and I’ve found some sources for searching that I knew nothing about! We all get lulled to thinking that Google is everthing, but not when the dark net is involved.


I had no clue this was even out there! Great Info! Good looking out!


That is without doubt one of the best things i have seen in my Life, Peothry in Motion, I love it, Keep up the good work and Thanks for sharing !

The Public

Maybe we can find Obama’s birth certificate… lol



Yohan Setiawan

wow this is very interesting…
thanks man..!


I have used DEVONthink and DEVONagent with some success (http://www.devon-technologies.com/), but I have to admit I am not really sure how is completes it’s searches. It is billed as a professional search and organization tool for journalists and researchers and I have been quite happy with it. (NOTE: Mac only)

joel gratulas

there’s no way size of the indexed web is 167 terabytes. i solely have a almost one terabyte of data in my computer. if you have a look at it, the article that wikipedia referenced is 13 years old – it’s date is 1997. besides the “popular” search engines are much more powerful now. imho, no matter how hard you try with these “deep web” search engines, you wouldn’t be able to come up with any web page that is not indexed by yahoo or google. maybe there are non-indexed pages on the web indeed, but the only reason is probably information security. and they’re supposed to be non-indexed, even by these “deep web” engines.

Roddy MacLeod

Latest: 10 interesting websites #8, as selected by Roddy MacLeod http://roddymacleod.wordpress….


Crap does no more a deep search than google, in fact worse than google or yahoo. waste of time.