PDF Compressor — Free, Private, Browser-Based
Reduce PDF file size for email attachments, web uploads, or storage. Compression runs entirely in your browser using PDF.js — your documents never leave your device.
How to reduce PDF file size for email
- Drop your PDF. Drag and drop one PDF file into the upload area, or click to browse. Multi-page documents up to 500 pages work fine.
- Pick a compression preset. Choose Low (best quality, smallest reduction), Medium (balanced — recommended for email), or High (maximum compression, may visibly reduce image quality).
- Wait for processing. Compression runs in your browser. A 40 MB PDF typically processes in 15–45 seconds depending on your device.
- Download the compressed PDF. Click Download to save the smaller PDF. Original file is unchanged.
Frequently Asked Questions
- Are my PDFs uploaded to a server?
- No. Compression runs entirely in your browser. Your PDFs never leave your device.
- How much can it shrink a PDF?
- Typical reduction is 40–80% depending on content. PDFs with high-resolution images compress most; text-only PDFs compress less.
- Does it work on password-protected PDFs?
- No. Password-protected PDFs must be decrypted first. We recommend using a desktop tool for sensitive encrypted documents.
- Is there a page limit?
- No hard limit. Performance depends on your browser memory. We have tested 500-page PDFs successfully on modern devices.
- Will text still be searchable?
- Yes. Text remains selectable and searchable. Only image and font data is compressed.
- Does compression add watermarks?
- No. Output PDFs have no watermark, branding, or trial limitations.
Use Cases
- Shrink a 40 MB PDF to fit a 5 MB Gmail attachment limit
- Reduce PDF size for college application uploads
- Compress resume PDFs to stay under job-board upload limits
- Make a scanned multi-page document easier to share
- Reduce ebook file size for tablet/Kindle transfer
Where PDF bloat actually comes from
A PDF is a container, not one file format — its size almost never comes from the text layer (vector text is tiny) but from embedded raster images: scanned pages, screenshots, or photos placed at print resolution (300 DPI) when the document is only ever viewed on screen. Compression works by re-processing those embedded images, not the text.
| Preset | What it changes | Typical reduction | Best for |
|---|---|---|---|
| Low | Re-encodes images at ~90% JPEG quality, keeps DPI | 10–30% | Documents with diagrams/charts where sharpness matters |
| Medium | Downsamples images to ~150 DPI + 75% JPEG quality | 40–70% | Email attachments, most scanned documents (recommended default) |
| High | Downsamples to ~96–110 DPI + 50% JPEG quality | 60–85% | Multi-page scans where file size matters more than image crispness |
- A scanned 20-page document at 300 DPI can easily hit 40 MB because each page is effectively a full-resolution photo; the same pages at 150 DPI (still perfectly legible on a screen) often come in under 5 MB.
- Fonts get subsetted too (only the glyphs actually used are kept), which matters for PDFs with embedded custom fonts but adds little compared to the image downsampling step.