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How To Compare Two PDF Files for Differences

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In today’s digital age, PDF files are ubiquitous. They are used in a myriad of applications, from business contracts to academic papers. There may be instances where you need to compare two PDF files for differences. This could be to check for revisions in a contract or to verify the accuracy of a document. In this article, we will explore several methods to compare two PDF files effectively.

Quick Answer

To compare two PDF files for differences, you can use tools like DiffPDF, pdfjam, pdftotext and diff, or online services like Each tool has its own strengths, allowing you to compare text, appearance, or both. Choose the tool that best suits your needs and follow the provided instructions to effectively compare and identify any differences between the two PDF files.

Using DiffPDF

DiffPDF is a dedicated tool for comparing PDF files. It allows you to compare the text on each pair of pages or the appearance of the pages. This is particularly useful when you want to spot differences in layout, formatting, or content.

To use DiffPDF, follow these steps:

  1. Open DiffPDF and load the two PDF files you want to compare.
  2. Choose whether you want to compare by ‘Appearance’ or ‘Characters’.
  3. Click on the ‘Compare’ button.

DiffPDF will then highlight any differences between the two PDF files.

Using pdfjam

pdfjam is a command-line tool that can concatenate PDF files into a long scroll. This is useful when you need to compare large sections of text or when sections have been inserted or removed.

Here’s an example of how to use pdfjam:

pdfjam file1.pdf file2.pdf --nup 2x1 --landscape --output output.pdf

In this command, file1.pdf and file2.pdf are the files to be compared. The --nup 2x1 parameter arranges the two files side by side. The --landscape parameter sets the orientation to landscape, and --output output.pdf specifies the output file.

Using pdftotext and diff

pdftotext is a command-line tool that converts PDF files to text. By comparing the text output of two PDF files, you can identify differences. This can be done using the diff command.

Here’s an example of how to use pdftotext and diff:

pdftotext file1.pdf file1.txt
pdftotext file2.pdf file2.txt
diff file1.txt file2.txt

In this command, file1.pdf and file2.pdf are the files to be compared. The pdftotext command converts the PDF files to text. The diff command then compares the text files and highlights any differences.

Using is an online tool that allows you to compare PDF and Word files. It provides a visual comparison of the files and can be useful for identifying differences.

To use, follow these steps:

  1. Go to
  2. Click on ‘Choose Files’ or drag and drop your files into the designated area.
  3. Click on ‘Compare Documents’. will then display a side-by-side comparison of the two files, highlighting any differences.


Comparing two PDF files for differences can be done using various tools, each with its own strengths. The choice of tool depends on your specific needs, such as whether you need to compare text or appearance, whether you prefer a command-line or graphical interface, and whether you want to install software or use an online tool. By understanding how to use these tools, you can effectively compare PDF files and spot any differences.

Can I compare PDF files for differences using DiffPDF on a Mac?

Yes, DiffPDF is compatible with Mac operating systems. You can download and install it from the official website.

Can I compare scanned PDF files using DiffPDF?

No, DiffPDF is primarily designed to compare the text and appearance of PDF files. It may not be able to accurately compare scanned PDF files as they are image-based and do not contain searchable text.

Can I compare more than two PDF files using pdfjam?

Yes, pdfjam allows you to concatenate multiple PDF files. You can specify multiple files in the command-line and compare them all at once.

Are there any limitations to using pdftotext and diff for comparing PDF files?

pdftotext and diff rely on the conversion of PDF files to text for comparison. Therefore, if the PDF files contain complex formatting, images, or non-standard fonts, the comparison may not be accurate. It is best suited for simple text-based PDF files.

Can I compare PDF files with different page sizes using

Yes, can handle PDF files with different page sizes. It will automatically adjust the display to accommodate the varying page sizes for an accurate comparison.

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