Stax

PDF Compressor

Reduce PDF file size using lossless compression.

Click to upload a PDF to compress

Reduce PDF file size in-browser

Compress PDFs using lossless structural optimisation: object stream compression and metadata removal. Best for PDFs with redundant structure. No images are recompressed, so quality is preserved.

Frequently asked questions

How much can this tool reduce my PDF size?
Results vary. PDFs with redundant cross-reference tables, unused objects, or verbose metadata can shrink by 10–40%. Tightly-optimised PDFs from professional tools may not shrink at all. Image-heavy PDFs benefit most from compressing the source images before converting to PDF.
Why is my compressed PDF not smaller?
Many modern PDF generators already apply object compression. If the PDF was created by Chrome's print-to-PDF, Adobe Acrobat, or Word's export, it is likely already well-optimised. For image-heavy PDFs, use the Image Compressor first, then convert to PDF.
Does compression affect PDF quality?
The compression used here is lossless — it only removes structural overhead and metadata, not image or text data. Visual quality is identical to the original.

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