PDF (Portable Document Format) is a versatile and commonly used file format for sharing and presenting documents, but sometimes you need to compare two PDFs side by side to detect differences or verify accuracy. Thanks to a range of online and offline tools, comparing two PDF documents has never been easier.

Here are some of the best tools to compare two PDFs side by side:

1. Adobe Acrobat Pro DC: Adobe Acrobat Pro DC is a premium PDF editing software that allows users to compare two PDF documents side by side either as a view or a list of differences between the two documents. The tool is easy to use and supports both Windows and Mac platforms. Adobe Acrobat also comes with a free trial version to try out the software before purchasing it.

2. Draftable: Draftable is an online tool that compares two PDF documents side by side and highlights the differences, making it easy to identify changes between documents. The tool is free to use for up to ten comparisons per month, and the Pro version offers more features such as document merging and redaction.

3. DiffPDF: DiffPDF is a free PDF comparison tool for Windows, macOS, and Linux, which allows users to compare two PDFs side by side and highlight differences between the two documents. DiffPDF highlights the differences between the two PDF documents in a clear and organized manner, making it easy to spot changes.

4. Foxit PhantomPDF: Foxit PhantomPDF is another premium PDF editing software that allows users to compare two PDF documents side by side. The software provides a document view and highlights the differences between the two documents. Foxit PhantomPDF also supports a free trial version for users to test out the software.

5. PDF-XChange Editor: PDF-XChange Editor is a PDF editor that allows users to compare two PDF documents side by side. The software provides a document view and highlights the differences between the two documents. PDF-XChange Editor is available as both a free and paid version, with the paid version offering additional features like the ability to create and edit PDF documents.