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Compress PDF
Reduce your PDF file size while preserving quality — processed entirely in your browser, never uploaded.
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Drop PDF files here
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🔒 Your files stay on your device
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Reduce your PDF file size while preserving quality — processed entirely in your browser, never uploaded.
Select the PDF file you want to make smaller. PDFably shows the original file size immediately.
Click Compress and PDFably optimizes the internal structure of your PDF. Processing is instant and happens on your device.
See exactly how much smaller your file became. Download the compressed version and use it anywhere — email, web, or archive.
PDF files often contain more data than necessary. Editing software may leave behind orphaned objects, duplicate font subsets, or metadata from previous versions. PDFably's compressor analyzes and rebuilds the internal structure, consolidating redundant data and applying efficient object stream compression.
The key technical mechanism is object stream optimization. A PDF consists of indirect objects — pages, fonts, images, metadata — stored in a cross-reference table. PDFably reorganizes these objects into compressed streams using the FlateDecode filter (zlib compression), which significantly reduces overhead without altering any visible content.
This approach is different from aggressive compression tools that re-render images at lower resolution. PDFably preserves every pixel of your images and every glyph of your text. The savings come purely from structural optimization — eliminating waste, not quality.
Email providers typically cap attachments at 10-25MB. If your PDF exceeds that, compression is the fastest fix. Most business documents compress well enough to slip under these limits without any visible difference.
Web upload forms — job applications, government portals, insurance claims — often impose strict file size limits. Compressing your PDF before uploading avoids frustrating rejections. Similarly, cloud storage users can reclaim significant space by compressing archived PDFs that don't need frequent access.
Loading speed matters too. If you embed PDFs on a website (manuals, whitepapers, product catalogs), compressed files load faster for visitors, improving user experience and reducing bounce rates.
Results vary depending on the file. Text-heavy PDFs typically compress by 15-30%. PDFs with unoptimized images can shrink by 40-70%. The tool optimizes internal structures without degrading visible quality.
No. Text remains perfectly sharp because PDFably optimizes the file structure and object streams — not the content itself. Fonts, vectors, and text rendering are untouched.
Some PDFs are already well-optimized, especially those created by modern software like Adobe Acrobat. If the original was efficiently encoded, there's less room for further compression.
No server-side limit. Since compression runs in your browser, the practical limit depends on your device's available memory. Most modern devices handle files up to 200MB+ without issues.
Currently, PDFably compresses one file at a time. Upload a new file after each compression. Batch processing is planned for a future update.