Reduce PDF file size quickly with our free online PDF Compressor. Choose Extreme, Balanced or Quality compression — all processing happens offline in your browser.
Results 0Original size vs. compressed size, with the space you saved.
How to Compress a PDF in 3 Simple Steps
1
Upload PDFs
Drag & drop one or more PDF files into the upload area, or click Choose PDFs.
2
Pick a Level
Choose Extreme for max reduction, Recommended for balance, or Less to keep quality. Adjust advanced options only if needed.
3
Compression
Click Compress PDFs. Review the size savings per file, then download individually or as a ZIP.
What is a PDF Compressor?
A PDF compressor reduces the file size of a PDF document while preserving as much of its readable content as possible. Most bloated PDF files become large because they were scanned at very high DPI, contain embedded fonts, carry duplicated resources, or store legacy metadata that no longer serves any purpose. A good compressor rewrites those parts — re-encoding oversized images at a smarter resolution, stripping metadata, removing unused objects, and packing the final file with object-stream compression.
Three Compression Levels for Every Need
Sigify ships with three carefully tuned presets so you don't have to guess the right trade-off:
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Less Compression
Minimizes quality loss at the cost of a smaller size reduction. Best for final-print documents and archival files.
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Recommended Compression
Balanced size reduction with great visual quality. Designed to handle mixed-content PDFs, image-heavy PDFs and standard office documents.
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Extreme Compression
Maximum size reduction at the cost of some image quality. Ideal for email attachments, web uploads, and large scanned archives where every kilobyte counts.
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Removes Metadata
Strips author, creation timestamps and editing history by default — your PDF leaves with only the data it actually needs.
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Re-encodes Images
Optimizes embedded JPEG and PNG streams, downscales oversized scanned pages, and re-rasters at the chosen DPI when needed.
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100% Private
Everything runs in your browser. Your PDFs never leave your device.
How Sigify Compresses a PDF
Sigify uses two battle-tested open-source libraries:
PDF.js (Mozilla, Apache-2.0) — to walk the PDF page tree and extract the embedded images.
pdf-lib (Andrew Dillon, MIT) — to rebuild a new PDF, swap the optimized images back in, strip metadata and save with object-stream compression.
Combined with optional downscale (72, 96, 150 DPI) and JPEG quality (Low / Medium / High), Sigify can typically shrink an image-heavy PDF by 40–85% with no noticeable loss, and a text-only PDF by 10–30% while keeping every character crisp.
Why Compress PDFs?
Large PDFs slow down email, fail to upload to online forms, exhaust your cloud storage, and frustrate the people you share them with. Compressing them keeps the same content while making them easier to send, archive and load on every device. Sigify's privacy-first approach means you can process confidential contracts, legal filings and personal scans without ever trusting someone else's server.
Sigify — Free Online Tools for PDF, Image and Digital Utilities. Fast, private, browser-based tools you can trust.
Frequently Asked Questions – PDF Compressor
Everything you need to know about compressing PDFs with Sigify.
A PDF compressor reduces the size of a PDF file. Sigify does this by re-encoding embedded images at a smarter resolution and quality, removing unneeded metadata, dropping duplicate resources, and packing the final output with object-stream compression.
Yes, completely free. No signup, no hidden fees, no premium tier, no daily limit. Every Sigify tool is free forever.
It depends on the level and the content. Less Compression produces near-identical output. Recommended is barely distinguishable from the original for normal use. Extreme trades some image detail for a much smaller file — fine for screen viewing, less ideal for high-quality print.
Yes — up to 100 MB per file, processed entirely in your browser. For largest files, use a desktop browser on a machine with enough free RAM. (Sigify never uploads, so there is no server-side limit.)
Yes. Drop or select many files and Sigify will queue them and process one after another. You'll see the result card for each file as it finishes, and you can download them individually or together as a ZIP via Download All.
No. Sigify's PDF compressor runs entirely in your browser. Your files never leave your device. Nothing is sent to any server, nothing is logged, nothing is shared.
This PDF is password-protected and cannot be compressed without unlocking it. Please remove the password in your PDF reader first (e.g. "Save without password"), then re-upload the unlocked copy.
Most email providers reject attachments over 25 MB. Selecting Extreme often brings a 60-page image-heavy PDF from 80 MB down to under 10 MB — well within Gmail, Outlook and any corporate mail gateway.
Related Sigify Tools
Looking for something else? These related browser-based tools work the same way —
free, instant, and 100% private.