Compress PDF Online
Reduce PDF file size for email, uploads, and faster sharing without sending files to a server.
Drag & drop a PDF file here
or click to select a file
🔒 All processing happens locally in your browser. Your files never leave your device.
What's Next?
After you compress a PDF, turn it into images or merge it with other documents:
How to Compress PDF Files - Step by Step
Upload Your PDF
Drag and drop your PDF file or click to browse. Your file stays on your device - no uploading to servers.
Choose Compression Level
Select Low for best quality, Medium for balanced results, or High for maximum file size reduction.
Download Compressed PDF
Click compress and download your smaller PDF file. Compare the before and after file sizes.
Why Choose Our PDF Compressor?
Reduce PDF File Size Quickly
Choose a compression level based on whether you want the smallest file, the best quality, or a balanced middle ground.
Useful for Email and Upload Limits
Shrink large PDFs before sending them by email, uploading them to portals, or sharing them with clients and teammates.
Private Browser-Based Compression
Your document stays on your device while PDFKit compresses it locally in the browser.
Simple Quality Controls
Test low, medium, or high compression and compare the size savings before you download the final file.
Frequently Asked Questions
Private PDF workflow
What this Compress PDF tool is best for
Use PDFKit to make large PDFs easier to email, upload, and share. The compressor runs in your browser and gives you quality controls before download.
Why compressing a PDF in your browser is different
Most online PDF compressors work by uploading your file to a server, compressing it there, and sending it back. That means your bank statement, signed contract, or medical report sits on someone else's machine — often with a vague retention policy. PDFKit takes a different route: the compression engine runs as WebAssembly inside your browser tab, so the file never crosses the network. If you switch off your Wi-Fi after the page loads, compression still works.
What actually shrinks in a PDF? Almost always the images. A scanned 10-page document is really 10 large photographs wrapped in a PDF container, which is why scans compress dramatically — often 70–90% smaller — while a text-only PDF exported from Word barely changes, because text is already stored compactly. PDFKit re-encodes embedded images at a lower quality level and strips redundant data, which is why you get a quality slider instead of a single "compress" button.
Practical targets: most email providers cap attachments at 20–25 MB, Gmail at 25 MB, many government and university portals at 2–5 MB, and some job application systems at just 1 MB. Compress toward the limit you actually face rather than picking maximum compression by default — heavy compression on scans can make small print hard to read.
If the compressed file is still too large, the usual culprit is page count rather than image size. Split the PDF into sections first, then compress each part — the Split PDF tool handles that without re-uploading anything.
Common use cases
- Email attachment limits
- Government or university upload portals
- Scanned PDFs with large images
- Client reports that need a smaller file
Formats and privacy
Input: PDF. Output: compressed PDF.
The PDF is processed locally in the browser, so document contents do not need to be uploaded to a server.
Things to check before sharing
- Text-only PDFs may not shrink much because they are already compact.
- High compression can reduce image sharpness.
- Password-protected PDFs may need to be unlocked first.