Two compression modes
Lossless mode restructures the file with identical quality. Strong mode re-encodes pages as optimized images for maximum size reduction on scans.
Compress PDF
Shrink PDFs for email and uploads — without sending them to a server.
or drop a file here
Files are processed in your browser and never uploaded.
Compress PDF online — free and private
Compress PDF reduces the size of your PDF so it is easier to email, upload or archive. Choose Lossless mode to optimize the internal structure of the file with zero quality change, or Strong mode to aggressively shrink scanned and image-heavy documents by re-encoding pages.
As with every PDF10x tool, compression runs completely inside your browser. Your file is never uploaded, which means no privacy risk and no waiting for large uploads and downloads.
Why use PDF10x to compress pdf?
See savings before download
PDF10x shows the original size, the new size and the percentage saved, so you know exactly what you gained.
Private and instant
No upload queue, no server. Compression starts immediately on your device and your document stays yours.
How to compress pdf online
- 1
Select or drop the PDF you want to compress.
- 2
Pick a mode: Lossless for documents with text you may copy, Strong for scans and image-heavy files.
- 3
Click “Compress PDF” and watch the size drop.
- 4
Download the compressed file and check the size savings.
Frequently asked questions
Which compression mode should I choose?
Use Lossless when you need selectable text and perfect quality — it optimizes the file structure without altering content. Use Strong for scanned documents or image-heavy PDFs where the biggest size reduction matters more than selectable text.
Why is my PDF barely smaller in Lossless mode?
Lossless mode removes redundancy in the file structure. If your PDF was already well optimized, or its size comes almost entirely from photos, the structural savings are small. Strong mode will reduce it much further.
Does Strong mode change my document?
Strong mode re-renders each page as an optimized image. The document looks the same, but text is no longer selectable. Keep the original if you need to copy text later.
Is there a file size limit?
There is no hard limit. Processing happens on your device, so very large files are limited only by your browser's available memory.