365tools

Compress PDF

Reduce PDF file size while preserving quality. Instant and private.

Files processed in your browser — never uploaded

How Compress PDF Works

1

Upload your PDF

Drop your PDF file onto the upload zone or click to browse. The original file size is shown immediately.

2

Click Compress

Hit the Compress button. The tool restructures the PDF using object streams to reduce file size without re-rendering content.

3

Download & see savings

See the original size, compressed size, and percentage saved — then download the optimized PDF instantly.

Key Features

Visible Size Reduction

After compression, you see the original size, new size, and exactly how much space was saved before you download.

No Quality Loss

Compression uses PDF object stream optimization — text, images, and vector graphics are preserved at original quality.

Instant Processing

Compression happens entirely in your browser with no server queues. Results are available in seconds.

100% Private

Your PDF is never uploaded to any server. All compression happens locally using pdf-lib in your browser.

All PDF Types

Works with PDFs from any source — scanned documents, exported reports, presentations, forms, and more.

Sensible Filename

The downloaded file is automatically named with a "-compressed" suffix so you can tell it apart from the original.

Frequently Asked Questions

Q
How much can a PDF be compressed?
A
Results vary by PDF type. PDFs with lots of redundant metadata, unoptimized cross-reference tables, or inline objects can see 10–40% reduction. Already-optimized PDFs may see little change. Scanned image PDFs require image resampling (not currently supported) for significant size reduction.
Q
Will compressing a PDF reduce image quality?
A
No. The compression method used (pdf-lib object stream optimization) restructures the PDF's internal data without resampling or re-encoding any images or text. Visual quality is completely preserved.
Q
Why is my PDF not getting smaller?
A
If a PDF was already optimized or is mostly composed of scanned images, the object-stream compression may have little effect. PDFs that contain uncompressed streams, duplicate objects, or unoptimized cross-references benefit most from this type of compression.
Q
Does this work with scanned PDFs?
A
Yes, but size reduction will be minimal for scan-heavy documents. Scanned PDFs are dominated by large image data. To significantly compress them, you would need image resampling — which is a more complex operation we may add in a future version.
Q
Is my PDF uploaded to a server?
A
No. All compression is performed in your browser using the pdf-lib library. Your file never leaves your device.
Q
What is the maximum file size I can compress?
A
There is no server-imposed limit. The practical limit is your device's available memory. Most documents up to a few hundred megabytes are processed without issue.
Q
Can I compress a password-protected PDF?
A
No. Encrypted PDFs need to be decrypted before they can be restructured. Remove the password protection first using your PDF viewer, then compress.

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