Compress PDF
Shrink file size for easier sharing while keeping high visual quality.
Drop a PDF to compress
or click to browse
Up to 25 MB per file
About Compress PDF
Compress PDF reduces the size of your PDF document so it’s faster to email, easier to upload and friendlier to mobile data plans. NinjaPDF rewrites the file’s internal structure using object streams and removes redundant data — all in your browser, with no quality loss for vector content and minimal impact on images.
How to use Compress PDF
- 1
Drop your PDF into the upload area or pick it from your device.
- 2
Click ‘Compress PDF’ and NinjaPDF will optimize the file structure locally.
- 3
Compare the before/after sizes shown on the page.
- 4
Download the smaller PDF — the original on your device is untouched.
Why use NinjaPDF
- Lossless restructuring keeps text and vectors crisp
- Faster sharing over email and chat
- Reduces storage costs in cloud drives
- No watermark added to the output
- 100% local processing — nothing uploaded
- Free for unlimited use
Frequently asked questions
How much can I compress a PDF?+
Savings vary. Text-heavy PDFs typically shrink 10–40%. Image-heavy PDFs that have already been optimized may see smaller gains.
Will compression reduce the quality?+
NinjaPDF’s in-browser compression is lossless — it reorganizes the document’s structure rather than re-encoding images, so quality is preserved.
Is the compressed file safe to share?+
Yes. The output is a standard PDF that opens in any reader, including Acrobat, Preview, Chrome and mobile apps.
Are my files uploaded to your server?+
Never. All compression happens in your browser; the file never leaves your device.