What is it?
As it says, PDFster.net is a meta search engine for PDF documents.
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Overview
PDFster is a meta search engine for finding PDF documents on the web. While it is very basic in appearance and function, I have found it to be a valuable and helpful tool for researching the commerical aviation industry. One of the main advantages to a PDF-specific search engine is that by confining the search target to just PDFs, there is a much higher yield of relevant results. For example, most airline industry-related Google searches deliver irrelevant results related to buying tickets or finding low fares ("travel spam"). Obviously, this kind of search will only be useful if the information you are searching for is typically published in PDF documents.
Examples of what you will (usually) find include:
- Academic Journals/Papers/Articles
- Government Reports
- Legal Documents
What you wont find:
- Blogs
- Websites
- Videos
- Images
How do I use it?
PDFster can be a great research tool for finding PDF documents on the web. Here's how to use it:
Start Page
- The PDFster start page is fairly simple, with the search dialog box in the upper-right corner
- For convenience, tags of frequently searched topics are listed
- The only drawback is the advertising on the side of the page is slightly annoying.
For the purpose of this demonstration, let's use [aviation industry] as the search query
Results
- For [aviation industry], PDFster delivers 5,520,000 Results
- However, the relevance of results may be an issue. As you can see in this set of results, there are valuable PDFs shown amongst other less helpful results.
- In my experience, after modifying your search queries, it is possible to retrieve more relevant results. For this example, other suggested queries could be [airline industry], [airline performance], or [commercial aviation].
- Another useful feature of PDFster is that the PDFs can be saved to your computer with one click by using the [save to disk] feature.
Observations
While PDFster is easy to use, in order for it to be a useful tool, the user must be searching for the kinds of documents that PDFster can easily produce. Many times, the documents are much more sophisticated and written at a higher difficulty level than the average web site. For example, a search query of [commercial aviation industry] will provide in-depth industry reports and analyses from many academic and government organizations. For a user researching the industry at such a deep level as myself, the results are superior to a standard web search. If I were simply looking for news events or information regarding a specific airline, I would be better off with Google.
Opacity
Despite being a "meta" search engine, PDFster is not very transparent. It fails to provide the user with the sources being searched.
Quality of Coverage
On the back end, it is hard to tell the overall breadth, depth, and quality of the directories searched due to the opacity of PDFster. However, the quality of the document set is typically very high. From an academic point of view, the results are often from well-respected institutions. In the [commercial aviation industry] query, the top results included documents from Harvard Business School, Wharton, and the Federal Aviation Administration.
Format of Results/Content
The results are formatted very well and in a user-friendly manner. Clicking on the link will open the PDF document in a new window, but there are also options to save the PDF to disk, delicious, and digg right in the results listing. None of the other PDF search engines comparable to PDFster have the digg or delicious features. The search engine is ad-supported so there are ads placed within the results and in the margins, but they are just a minimal distraction in my opinion. For convenience, PDFster also suggests relevant websites and alternative search queries.
Special Queries?
Perhaps the biggest drawback of PDFster is that it lacks the ability to use operators like and, or, inurl, etc. in search queries. Furthermore, there is no Advanced Search function like many other search engines. This limits the capabilities of the search engine to only perform simple queries. An ability to perform more dynamic searches will greatly increase the usefulness of PDFster.
Comparisons
The following are additional PDF search engines comparable to PDFster. Some are better, some are worse. The "relevancy" rating is simply the ratio of relevant results given in the first ten results for the [airline industry] query.
PDFster has a relevancy of 8/10
Pdf-search-engine
Relevancy: 9/10
Pdf-search-engine.com has the highest traffic of the comparable search engines. Despite the nice and clean appearance of the start page, pdf-search-engine.com has about the same power as PDFster and is slightly less easy to use. It is slow—the results and PDFs take years to load. One nice feature is the ability to view docs in plain-text HTML. While the results are relevant, the engine only seaches ebooks which overlooks many potential PDFs that may be relevant. Verdict: on par with PDFster.
PDFGeni
Relevancy: 6/10
PDFGeni has the second-highest traffic of the search engines. Like pdf-search-engine.com, PDFgeni searches only ebooks which may overlook potential relevant results on the web. PDFgeni is even less useful because the results are listed in a cluttered and inconvenient manner. At first, I was excited the [airline industry] seemed to have lots of relevant results but on further inspection, many were just the tables of contents for different ebooks. The resulting relevancy is much lower. Verdict: less useful than PDFster.
PDFQueen
Relevancy: 9/10
Weird name aside, this search engine is pretty great. High relevancy, quick, and the results are displayed in an easy-to-use format. There is still the option to save to disk with one click as well which is nice. Verdict: better than PDFster.
PDFind
Relevancy: 2/10
PDFind is sub-par in multiple ways. The graphics make the site look cheap, and confusing to read. It delivers an awfuly small set of 45 documents for [airline industry] which seem to appear from all different corners of the internet. Relevancy is very low. Verdict: Fail.
Traffic Comparisons
Red: pdf-search-engine.com
Yellow: pdfgeni.com
