Compress PDF
Reduce the file size of your PDF while maintaining optimal visual quality for uploads and email attachments.
Select PDF file
or drag and drop PDF here
Optimization Guide: The Mechanics of PDF Compression
PDF files can become bulky when they contain high-resolution images, embedded fonts, and complex vectors. Compressing a PDF involves optimizing these assets to reduce file size without compromising readability.
Lossless vs. Lossy PDF Optimization
PDF compression uses two main methods: lossless and lossy. Lossless compression shrinks text streams using algorithms like FlateDecode (Deflate). Lossy compression targets raster images embedded in the document, compressing JPEG data or downsampling images (e.g. from 300 DPI to 150 DPI) to dramatically reduce file sizes.
The Security Advantage of Local Compression
Because PDFs often contain financial statements or confidential records, uploading them to public cloud servers for compression poses privacy risks. DocumentAlter compresses PDFs directly in your browser, keeping your sensitive documents secure.
How to Compress PDF (Step-by-Step Guide)
Import Target PDF File
Select or drag the PDF document you want to optimize into the compression area.
Configure Optimization Strength
Choose your compression level: Recommended (best quality/size ratio), Extreme (maximum size reduction), or Low.
Optimize and Download
Run the local optimization script to re-compress the document and download the smaller file.
Frequently Asked Questions
Drop your PDF into our tool, select your compression strength, and click 'Compress PDF' to optimize the file size locally.
Our recommended setting optimizes file sizes while maintaining clear readability for text and images.
Yes. All calculations run in your local browser sandbox, keeping your documents confidential.