Secure PDF Compressor
Reduce PDF file sizes instantly. 100% private, browser-side processing. Your files never leave your device.
Compression Level
Currently re-encodes JPEG images only — PDFs whose images are PNGs (common in pasted screenshots) won't shrink much yet.
Awaiting PDF
Upload a document to begin optimizing its file size.
Why Use a Local PDF Compressor?
When dealing with signed contracts, financial reports, or personal identification, uploading your documents to a random "Free PDF Compressor" website is a massive security risk. Most traditional online tools transmit your raw files to a remote server, process them, and send them back. This exposes your sensitive data to potential interception, server logs, or unauthorized retention.
Our Secure PDF Compressor fundamentally shifts this paradigm. By leveraging a Web Worker and the browser's Canvas API, we bring the compression engine directly to your device. When you drag and drop a PDF, it is loaded into your browser's isolated RAM. The image extraction, downsampling, and document rebuilding happen entirely on your CPU. Once the compression is complete, the file is saved directly to your hard drive. Zero bytes are transmitted over the network.
Smart JPEG Re-encoding
The primary culprit behind massive PDF files is high-resolution embedded images. Our tool scans the internal document tree for JPEG images, extracts them, and uses your browser's native Canvas API to re-encode them at a web-friendly resolution and quality, preserving legibility while slashing file size. Only the image is touched — every other object in the file is left as-is.
One Current Limitation: PNG Images
Today, the re-encoding step only handles JPEG images (the most common format for scanned pages and photos). PDFs whose embedded images are PNGs — common in pasted screenshots or diagrams exported from Word or Google Docs — will see little to no size reduction from this tool yet, since those images are currently left untouched rather than re-encoded.
Frequently Asked Questions
Popular Target Sizes
Need to compress your PDF to a specific size for an email attachment or online application? Use our pre-configured dedicated tools:
Recommended Learning Guides
Master the technical concepts behind this developer utility.
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