Comparing two PDF files to find possible changes is a very exhausting and time-consuming process. Several rounds of revision in a document can make changes slip by. If such documents contain a great deal of information, the comparison process may take hours, if not days.

A lot of people who compare documents on a regular basis use specialized software that can highlight or change aspects of the document during revision. With PDF being the most popular format, let's discuss some tools that can help you compare PDFs.

1. Adobe Acrobat

Adobe Acrobat is a pre-installed, go-to PDF viewer and editor for the majority of Windows users. You can view and edit your PDF documents with their free version.

To enjoy advanced features like combining multiple files, extracting few sections, splitting files into smaller chunks, and comparing PDFs, you'll have to subscribe to its premium version. Check the pricing of Adobe Acrobat.

With its premium version, the powerful tool makes it so much easier to spot differences between two files with its Compare option. It highlights the edited text and the images and marks what’s added, removed, or modified so that you can compare the PDFs with a side-by-side preview of the documents.

After comparing both files, it also generates a clean comparison report that helps you quickly navigate through future changes. Adobe Acrobat is supported on Windows, macOS, and Android. If your pockets don't allow you to spend money on such software, sit tight, as we'll cover some free alternatives.

2. Diffchecker

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As the name suggests, Diffchecker is a free PDF comparison tool that specializes in comparing files in different formats. It highlights the altered paragraphs and text, making it very conspicuous. After comparison, it gives a clean report specifying the changes made in the document. One can also view the changes in the side-by-side preview.

The ideal software for infrequent users, Diffchecker is supported on both Windows and macOS and has a web app. However, the desktop app and some other advanced features do require a small subscription fee of $9.

3. Copyleaks

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Copyleaks is mainly used as a plagiarism detection tool, but the site also has a handy Text Compare tool that supports comparing files in different formats. Further, Copyleaks has recently introduced a multi-language adaptability feature by which you can compare PDF files in multiple languages.

By registering, you'll get a free trial, for which you’ll be limited to scanning a certain number of pages. Once you have used up your page count, you'll need to subscribe to a minimum monthly plan of $10.99, which allows you to scan 100 pages or 25,000 words. Copyleaks is supported on Windows, Linux, and macOS, and it is recommended to use this tool in either Firefox or Chrome browsers.

4. DiffPDF

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DiffPDF is specifically targeted toward PDFs, and users can compare reports, books, and labels as well. What gives DiffPDF an edge is that it is completely free. You don't need to register an account to get started. All you need to do is download the software, launch the app, upload your files, and click Compare. The differences will be highlighted in red.

It is safe to use and has no limitation on the number of pages or the size of compared files, giving this tool an advantage over others. The interface is also quite customizable for a better experience.

5. Draftable

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Draftable is a cloud-based software that also serves as a PDF comparison tool. It can compare and cross-check documents of different formats, making it easier and quicker to compare files that do not share a common format. It can detect the minutest of changes and then form the end result report into a PDF file ready for download.

As shown above, it highlights changes and then segregates them according to their nature on a separate panel beside the two side-by-side views of the files. Draftable is supported only in Windows and online, the online version being completely free and user-friendly, although it has a limit of 300 pages.

To avoid hitting the limit so quickly, you can try deleting pages from your PDF file first before proceeding. Still, if you wish to enjoy the maximum benefits without any restriction, consider subscribing to its paid plan, which can cost around $129 annually.

6. Aspose

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Aspose is an online software that comes with a wide range of services, including a file converter, file splitter, PDF editor, PDF document parser, and of course, a PDF comparison tool. You simply drag and drop a file, after which it runs a quick scan and highlights the changes made to the file.

You can also download the generated report as a PDF document. The only downside is that it does not provide a side-by-side comparison. While most of its other features can cost you hundreds of bucks, the basic functions of PDF comparison, editing and viewing are free.

7. KIWI PDF Comparer

KIWI PDF comparer comes with a user-friendly interface. It has two separate modes for comparison. The first one shifts through the document and distinguishes the different types of changes made: modification, insertion, deletion, or movement of text. The second ‘Pixel to Pixel’ mode treats the PDFs as if they were images and checks them accordingly.

The perfect algorithm of the KIWI PDF comparer also allows you to scan a few designated sections of the document. You can customize the color and the thickness of the highlight, and even have the option of dealing with highlighted text over a textured background.

Supporting a vast range of tools, KIWI comes in both paid and free versions, the paid with its added benefits, and the free with some limitations. The free version has a limit of 20 pages for comparing PDFs, and for advanced tools, you will need to upgrade to the premium version. KIWI can be run across Windows, macOS, and Linux.

8. ABBY FineReader​​​

Like Draftable, ABBY FineReader has the ability to compare and cross-check documents of different formats. It is a paid software, but you can enjoy its limited free trial period.

The software also has an inbuilt editor feature that allows you to change and edit documents, scanned images, and more on the go without the need to switch software every time you find a minor mistake. Once the documents have been scanned and dealt with, you can easily convert them into the desired format: Excel, Word, PDF, and more.

ABBY FineReader is supported on Windows, macOS, and Linux. Its paid plan can cost somewhere around $69, $99, to $165 a year, depending on which type of offer you are subscribing to.

9. PDFelement

Wondershare is a software company that offers a variety of tools to help you download any video from the internet for free and even remove passwords from locked PDF files. To compare PDF files, the app to use is PDFelement, which is available for both Windows and Mac.

First, download PDFelement from Wondershare's website and install it on your computer. Comparing PDFs is a paid feature, but you can test it out by registering for a free trial period. Among the actions available for PDF files, choose Compare and upload your two files.

After comparing your PDF files, PDFelement will categorize the differences by highlighting them with different colors. For example, you'll see green highlights for modified words and red highlights for deleted ones. For files with lots of pages, you can avoid missing out on any changes by clicking Next Change to jump to the next edited section in the file.

You can also filter the differences so that you can focus on checking the amount of new content added, for example. The paid plan to gain access to unlimited PDFelement features starts from $79.99 per year.

Compare PDFs Like a Pro

The above tools will help you compare two PDF files and analyze the changes being made in the documents. Always password-protect your PDFs containing confidential information before sharing them for revisions.