Compress PDF files
Reduce file size while optimizing for maximal PDF quality.
What is Compress PDF?
Reduce PDF file size without losing quality. Lossless in-browser compression that optimizes structure with zero server uploads and no file limits.
When should you use it?
This tool is useful when you need a smaller file, a more robust file, or text you can reuse in another application.
How Compress PDF handles your file
pdf-lib re-serialises the file in your browser tab. No bytes leave your device.
Your device's own CPU does the work, so there is no upload wait and no server-side copy of your document to retain.
Good to know before you convert
- Compression is lossless, so there is no image downsampling and no DPI setting. Savings depend entirely on how the original file was written.
- Files that are already tightly optimised may shrink only slightly, and a small number can grow because of re-serialisation overhead.
- A compression report listing the before/after size is downloaded alongside the PDF.
How to use Compress PDF
Upload your PDF document into the compressor container.
Choose a compression level: Extreme strips document metadata as well, Recommended keeps metadata, and Low Compression disables object streams.
Click the 'Compress PDF!' button to write the optimised file and download it, along with a size report.
Why choose PdfPix for Compress PDF?
Private by design
The file is never uploaded. Everything happens inside your browser tab, so there is no remote copy of your document to leak, retain, or subpoena.
No File Size Limits
Because conversions run locally using your computer's CPU power, we don't impose any artificial file size caps, queue delays, or wait times.
100% Free Forever
Get full access to all features without subscriptions, credit card inputs, or registration walls. No branding watermarks added to your outputs.
Universal Compatibility
PdfPix runs smoothly inside any modern browser on macOS, Windows, Linux, iOS, or Android, without needing external applications or plugins.
How PdfPixCompares to iLovePDF & Smallpdf
Unlike traditional cloud PDF services that upload your confidential documents to remote servers, PdfPix processes your files 100% in your browser. No file size paywalls, no task queues, and zero remote data retention.
Frequently Asked Questions
Does compressing a PDF reduce its visual quality?
No. PdfPix compression is lossless — it rewrites the file's internal structure and object streams instead of re-encoding images, so visible quality is untouched. Because nothing is re-encoded, the savings vary: files exported by large desktop suites often shrink noticeably, while already-optimised files may shrink very little.
Why is local PDF compression better?
It is faster, because you never wait to upload a large file, and it keeps your document on your own machine.
Can I compress password-protected PDFs?
You will need to unlock the PDF first using the Unlock PDF tool, because encrypted content streams cannot be re-serialised.
Related PDF tools
Repair PDF
Rebuild a damaged PDF's internal structure by re-parsing and re-saving it.
Extract PDF Text
Extract a PDF's text layer and flag the pages that still need OCR.
Merge PDF
Combine PDFs in the order you want with the easiest PDF merger available.
Split PDF
Separate one page or a whole set for easy conversion into independent PDF files.
Related guides from the PdfPix blog
Step-by-step articles that show how to get the most out of Compress PDF in real workflows.
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