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PDF Compressor

Make PDFs smaller for email and sharing

Recompresses embedded images at your chosen quality. No uploads, no account.

Image quality72%

Good for most uses

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How PDF compression works

  1. 1
    Upload your PDF

    Drop your PDF onto the tool. It's read directly in your browser — nothing is sent to any server.

  2. 2
    Choose a quality level

    Balanced (72%) is the default and works well for most PDFs. Use Screen for aggressive size reduction, or Print for near-original fidelity.

  3. 3
    Compress and download

    Each embedded JPEG image is decoded and re-encoded at your chosen quality level using the Canvas API. The resulting PDF is structurally identical to the original — only the image data changes.

Frequently asked questions

Is my PDF uploaded to a server?
No. All processing happens entirely in your browser using the Canvas API and pdf-lib. Your file never leaves your device.
How much will my PDF shrink?
It depends on what's in the PDF. Image-heavy PDFs — scanned documents, photo albums, catalogues — typically shrink 40–70% at Balanced quality. Text-only or vector PDFs have no images to compress and won't get meaningfully smaller.
What kind of images does it compress?
JPEG images (DCTDecode encoded), which are the most common type in real-world PDFs. PNG and other losslessly encoded images are skipped in v1 — they're typically small logos and diagrams that don't benefit from lossy compression.
Will the output look different?
At Balanced (72%) and Print (88%) quality, images look the same at normal viewing zoom. At Screen (50%) quality, you may notice some compression artefacts in large photos at high zoom. The text and vector content of the PDF is never touched.
Does it work with password-protected PDFs?
No. Remove the password first using your PDF viewer, then compress. The tool will show an error if it encounters an encrypted file.
My PDF has images but the tool says nothing was compressed — why?
The images are likely PNG-encoded (FlateDecode). These are already losslessly compressed and can't be made smaller with JPEG re-encoding without a quality trade-off. Future versions of the tool will handle this case.
Can I compress multiple PDFs at once?
Not yet — one file at a time for now. Bulk PDF compression is planned.