Compress PDF

What does the Compress PDF tool do?

The FreePDF Compress tool shrinks PDF file size in your browser using two methods. Safe mode rebuilds the PDF structure losslessly — nothing visible changes. Strong mode re-encodes each page as an optimised image, trading selectability for much smaller files.

Both methods run entirely on your device using pdf-lib and PDF.js, and the tool shows you the original size, compressed size and exact percentage saved before you download.

How to compress

1. 1
   Add your PDF

   Drag and drop or browse for the document you want to shrink.

2. 2
   Pick a method

   Safe mode keeps everything intact. Strong mode re-encodes pages as images for maximum savings.

3. 3
   Click Compress PDF

   The tool processes the file in your browser and shows the before/after sizes.

4. 4
   Download the result

   Save the compressed PDF if you are happy with the savings.

What FreePDF Compress PDF can do

• Safe lossless mode rebuilds PDF structure without changing content
• Strong mode re-encodes pages for maximum size reduction
• See exact size savings before downloading
• Works entirely in your browser — no file uploads
• No watermarks, no account needed

Privacy — your files stay on your device

Compress PDF runs entirely inside your browser using pdf-lib and PDF.js (Mozilla) — open-source, audited libraries with millions of users. Your files are loaded into browser memory, processed on your CPU, and written back out as a direct download. Nothing is sent to any server — you can verify this in your browser devtools → Network tab. Close the tab and everything is cleared from memory.

Supported devices and browsers

Known limitations

FreePDF is honest about what it can and cannot do:

• Strong mode converts pages to images: text is no longer selectable and links are removed
• Safe mode cannot shrink PDFs that are already well optimised
• Very large PDFs depend on your browser's available memory