What is Compress PDF?
Compress PDF is a free online tool that reduces the file size of a PDF in two ways. Smart mode performs a structural pass — recompressing object streams and baking page rotations — so text stays fully selectable. Maximum mode re-renders every page as an optimized JPEG image for scanned and image-heavy documents. Both run entirely in your browser, so files are never uploaded to any server.
Common Use Cases
Email Attachments
Shrink large PDFs so they fit within email attachment size limits and send faster.
Upload Limits
Reduce PDF file size to meet the upload caps of portals, LMS systems, and job applications.
Scanned Documents
Use Maximum mode to convert scan-heavy, image-only PDFs into much smaller optimized files.
Document Distribution
Lighten reports, manuals, and presentations before sharing or storing them in the cloud.
How to Use This Tool
- Upload a single PDF (up to 100 MB) by dragging and dropping or clicking the upload zone
- Review the page count and file size shown immediately after the file is read
- Pick a mode — Smart keeps text selectable, Maximum rebuilds pages as optimized images
- For Maximum mode, choose a resolution (120/150/200 DPI) and JPEG quality (40-85%)
- Click "Compress PDF" and watch the progress bar for the selected mode
- Compare the original and compressed sizes, then download the result as a <base>-compressed.pdf
Related Tools
Learn More
- ISO 32000-2 — PDF Specification ISO 32000-2, the official specification of the PDF file format and its compression options.