What is the best PDF file compressor for Windows 11?

Using Libre Office to Export PDFs with Compression, Libre Office is fundamentally a free, open-source office suite, not a dedicated PDF file compressor. You wouldn't install it just to shrink PDFs. But, if you already have it installed, its built-in PDF export feature can actually help you reduce file sizes, especially if the PDF started as a Libre Office document.

Instead of opening an existing PDF, you'd open the original document (like a .docx or .odt) in Libre Office Writer. Then, when you go to File > Export As > Export as PDF... , you get a settings window that has a surprising amount of control over the output.

This is where the compression magic happens. You can:

• Adjust JPEG Quality: The "Quality" slider under the "Images" section lets you lower the image quality, which drastically shrinks the file size. It's the same idea as any other good PDF file compressor.
• Downsample Images: You can tell it to lower the resolution (DPI) of all images, which is a great way to slim down a file intended for screen viewing.
• Avoid "Tagged PDF": This is a big one. The official Libre Office help documentation explicitly warns that enabling the "Tagged PDF" option "can increase file size by huge amounts". So, for compression, make sure that box is unchecked.

The major limitation is that Libre Office is not meant to directly edit existing PDFs. You can't just launch it, open a random PDF from the internet, and export a compressed version. For the PDF export settings to work their compression magic, you generally need the original, editable document that the PDF came from.

So, is Libre Office a good PDF file compressor? Yes, but only in a very specific workflow. If you're creating or editing a document and need to control the final PDF's size, Libre Office gives you excellent, fine-tuned control that's completely free.