I'd like to use Windows Search for searching through multiple PDFs in one go, but I see that in the Indexing Options' Advanced Options screen, PDF files don't have a registered IFilter: Registered IFilter is not found

What is an IFilter, and where can I get the appropriate one?

  • Not answering this old question, but I found DocFetcher useful.
    – Orion
    Jul 26, 2016 at 17:04
  • Could you drop by in Ask Different chat about bounty on your question, please?
    – user1038202
    Dec 22, 2019 at 16:07

7 Answers 7


IFilters allow Windows Search to search within file contents.

Here are three popular PDF IFilters:

After installing one, you should be able to search within PDF files in the same way that you can for other types of files.

PDF Filter

†:This article from 2009 has performance numbers, but they may not apply to current versions of the filters.

  • I tried this but it did not work for me. I'm on Windows 7 Professional (64-bit), with Adobe Reader X. I installed the iFilter, added it to my PATH environment variable, restarted my computer, and waiting until Windows was indexing, but I still couldn't search within my PDFs. I did have to install under my PC's administrator account, which is a different user, I wonder if that affected it. Jul 2, 2012 at 17:03
  • Did Windows finish indexing? Jul 2, 2012 at 19:52
  • @emddudley, if you want the PDF contents to be indexed, you should ensure that in the above screenshot, "Index Properties and File Contents" is selected for PDF files. Also, if you're searching non-indexed files, you may have to prefix your search query with content:.
    – Sam
    Jan 17, 2013 at 23:41
  • 1
    @Guillaume Not sure. I'm now on Windows 10 which is using a filter named "Reader Search Handler" which does well with sentences for me. I'm not sure where it came from. i.imgur.com/rVj1EhD.png Nov 22, 2016 at 3:59
  • 1
    @Louis Thanks for the feedback. Good to know. Problem solved on windows7, we just need to wait (much) longer for the pdf results (I did close the search window before it appears).
    – JinSnow
    Nov 22, 2016 at 5:27

An alternative way to search through PDFs is to use the search function of PDF-XChange Viewer. It does not need indexing neither. This is my choice.

You can install the portable version. Hit Ctrl Shift F to get the search dialog:

Search PDF in PDF-Viewer

  • 1
    Thanks, I didn't know this feature existed in the standard Reader. Sure is dang slow though. Dec 26, 2013 at 18:20
  • 2
    +1! Didn't know this. PDF-XChange Viewer is just awesome. Surprises me all the time.
    – Bloke
    Aug 30, 2014 at 21:04
  • 4
    Best answer in my opinion. Portable and very fast, even with preview and word location when clicked on a search result entry. Thanks for pointing out this gem.
    – Avatar
    Jul 18, 2019 at 5:24
  • Great option here, easy and very effective. Thanks
    – Valdemar
    Aug 20, 2021 at 11:03
  • I don't know wether to thank PDF-XChange Viewer but I downloaded it and searched through my Pdfs on OneDrive and it fixed the windows search results to search through pdf contents. Thanks man. Sep 12, 2021 at 16:23

You can use Mendeley; it's free.

First, add your PDF files and index them. After that, you can search them with auto-complete search.

  • You can also add notes on the PDF files with it.
  • If you have a lot a lot PDF files, sometimes RAM overflows when you try to index if this happen, just decrease count of PDF files.
  • Be careful, Mendeley actually is an academic program for reference system (yes, also you can use it for adding references to your Word document. I used it when I wrote my PHd Thesis; it was wonderful), so it will try to upload your PDF files to its server. If you want to work offline, change Mendeley's internet options and give it a wrong/offline proxy IP (like . Then you can work with it off-line. NOT: You can also search in HTML or word files with Mendeley.

PDF XChange Viewer, which has a free version available, comes with a built-in iFilter.


Maybe little free tool Pasco from Microsoft Store?

Pasco is a software whose main task is to search for pages in a text (pdf) containing a specified phrase. As the software indexes ebooks, the search result is displayed immediately. Pasco is not only a search engine but also a convenient ebook reader.


You can sort, filter pdf files based on title, pages etc using this shell extenion Debenu

Additionally, this portable application extracts all data from pdf files and produces a tabluar output which you can use in your workflow pdfinfogui

  • Are you affiliated with Debenu?
    – slhck
    Dec 31, 2013 at 8:25
  • 2
    No. I was facing a similar issue and had tried both the softwares. So, thought I will share the info.
    – Rahul
    Dec 31, 2013 at 12:10

Windows 10 has made great optimizations in content search, its goal is to do the search as convenient as Mac. So, if you are using Windows 10, you can build an index between to speed up the search speed, although this process is very slow and long.

For other earlier versions of Windows, you may need other third-party tools, such as: Docfetcher, Anytxt, are free and easy-to-use tools. Good luck.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .