Compress PDF
Optimize document structure to reduce file size. Best for text-heavy documents.
Upload PDF to Compress
Max file size: 50MB
Compress PDF File Size Online
Email attachments have size limits. Websites have upload caps. Storage space isn't infinite.UnitMaster PDF Compressor solves these problems by intelligently optimizing the internal structure of your PDF files to reduce their size without destroying their readability.
Frequently Asked Questions
How Does PDF Compression Work?
A PDF file is more than just text and images; it's a complex database of objects, fonts, and metadata. Our compression engine focuses on structural optimization:
- Object Streams: We group small PDF objects together into compressed streams.
- Metadata Stripping: We remove unnecessary editing history, thumbnails, and bloated metadata that doesn't affect the visual content.
- Font Subsetting: (In supported files) We ensure only the characters actually used in the document are embedded.
Lossless vs. Lossy Compression
Most online tools rely on heavy lossy compression—they take your crisp images and blur them to save space. UnitMaster prioritizes integrity. Our default mode is "Safe Compression," which focuses on reducing file overhead while keeping your text sharp and your images clear.
Is my data secure?
Yes. Just like all our tools, this compressor runs locally in your browser. We do not upload your sensitive financial reports or legal contracts to any server to compress them. You get the speed of a native desktop app with the convenience of the web.
More Questions
Best Practices for Small PDFs
Scan at 150 DPI instead of 300+. Use "Save as PDF" instead of "Print to PDF" for cleaner code.
Does it work on Mac?
Yes, it works on any device with a modern browser.