PDF Compressor
Reduce PDF file size. Free, no signup, no upload.
How It Works
Select a PDF file and click Compress. The PDF is re-serialized using pdf-lib, which removes unused objects, cleans up the cross-reference table, and optimizes the internal structure. The result is often 10-40% smaller. No file is ever uploaded to a server.
Why Compress PDFs?
Smaller PDFs are faster to upload, email, and download. Many platforms have file size limits for attachments. Compressing removes bloat from PDF editors, form data, metadata, and unused embedded resources.
What Gets Optimized
The compressor works on the internal plumbing of the PDF rather than the visible content, so nothing on the page changes. The table shows what it does and does not touch.
| Element | Handling |
|---|---|
| Unused objects | Removed |
| Cross-reference table | Rebuilt and cleaned |
| Redundant internal data | Discarded |
| Text and fonts | Preserved (lossless) |
| Embedded images | Left as-is, not recompressed |
Tips for Best Results
This tool shines on PDFs exported from word processors, design apps, and form fillers, which often carry hidden bloat. For scanned or photo-heavy PDFs where images are the bulk of the size, compressing here helps little — converting those pages to optimized images first, then rebuilding, is a better route. Large files are handled in your device's memory, so extremely large PDFs depend on how much RAM your browser has available.
Frequently Asked Questions
How do I compress a PDF file?
Select a PDF from your device and click Compress PDF. The tool rebuilds the file to remove bloat, shows the original and new size, and reveals a Download button. Click it to save the smaller PDF, which is named with a -compressed suffix.
Are my PDF files uploaded to a server?
No. Compression happens entirely in your browser using the pdf-lib library. Your file is read into memory locally and never sent, stored, or seen by any server, which makes it safe for confidential documents.
How much smaller will my PDF get?
It varies. The tool re-serializes the PDF, removing unused objects, cleaning the cross-reference table, and optimizing the structure, which often cuts 10 to 40 percent from files bloated by editors, forms, or metadata. If a PDF is already lean it may not shrink, and the tool will tell you so.
Why did my image-heavy PDF barely shrink?
This compressor optimizes the PDF structure but does not re-compress or downsample the images inside it. For scanned documents or PDFs that are mostly photos, the images dominate the size, so structural cleanup alone yields little reduction.
Does compressing reduce the quality of my PDF?
No. The process is lossless. Text stays sharp and images are left untouched, so the compressed PDF looks identical to the original. It simply discards redundant internal data that does not affect what you see.