Which compression level should I choose?

Use Low if you need the output to look identical to the original — good for archiving or printing. Use Medium for email attachments and web sharing where some quality trade-off is acceptable. Use High when file size is the priority — for quick messaging or uploading to size-limited platforms.

Will compression reduce text quality or legibility?

At Low and Medium levels, text remains sharp and easily readable. At High compression, text in image-heavy PDFs may show slight JPEG artifacts but remains legible. Pure text-based PDFs are less affected because text is replaced with JPEG renders of the page.

How does PDF compression work?

Our tool renders each PDF page to a canvas using pdfjs-dist, then encodes it as a JPEG image at reduced quality using the HTML5 Canvas API. These compressed images are then embedded into a new PDF document using pdf-lib. This approach works entirely in your browser without any server calls.

Are my PDF files uploaded to a server?

Never. The entire compression pipeline runs locally in your browser using WebAssembly. Your files never leave your device, making this tool completely safe for sensitive documents like contracts, medical files, and financial records.

Can I compress a password-protected PDF?

Password-protected PDFs that require a password to open cannot be compressed. PDFs with only print or copy restrictions (no open password) can generally be compressed without issues.

The compressed file is larger than the original — why?

This can happen with PDFs that already have heavily compressed content (e.g. already-compressed JPEGs), very short single-page documents, or PDFs with minimal image content. In these cases the original is already near-optimal and re-encoding adds overhead.

Which compression level should I choose?

Use Low if you need the output to look identical to the original — good for archiving or printing. Use Medium for email attachments and web sharing where some quality trade-off is acceptable. Use High when file size is the priority — for quick messaging or uploading to size-limited platforms.

Will compression reduce text quality or legibility?

At Low and Medium levels, text remains sharp and easily readable. At High compression, text in image-heavy PDFs may show slight JPEG artifacts but remains legible. Pure text-based PDFs are less affected because text is replaced with JPEG renders of the page.

How does PDF compression work?

Our tool renders each PDF page to a canvas using pdfjs-dist, then encodes it as a JPEG image at reduced quality using the HTML5 Canvas API. These compressed images are then embedded into a new PDF document using pdf-lib. This approach works entirely in your browser without any server calls.

Are my PDF files uploaded to a server?

Never. The entire compression pipeline runs locally in your browser using WebAssembly. Your files never leave your device, making this tool completely safe for sensitive documents like contracts, medical files, and financial records.

Can I compress a password-protected PDF?

Password-protected PDFs that require a password to open cannot be compressed. PDFs with only print or copy restrictions (no open password) can generally be compressed without issues.

The compressed file is larger than the original — why?

This can happen with PDFs that already have heavily compressed content (e.g. already-compressed JPEGs), very short single-page documents, or PDFs with minimal image content. In these cases the original is already near-optimal and re-encoding adds overhead.

Compress PDF – Reduce File Size Online

Shrink your PDF file size instantly — free, 100% private, browser-based. Choose Low, Medium, or High compression. Files never leave your device. No account needed.

Drop your PDF file here

or click to browse — PDF files only

Choose Files

How to Compress a PDF (4 Easy Steps)

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Upload your PDF

Drag and drop your PDF onto the upload area or click to browse. The tool shows your original file size immediately after upload.

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Choose compression level

Select Low (best quality, mild reduction), Medium (balanced), or High (maximum compression, smallest file). Pick based on your quality needs and sharing requirements.

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Compress the PDF

Click "Compress PDF" and the tool re-renders each page at reduced quality and rebuilds the PDF in your browser. A live page counter shows real-time progress.

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Download & compare sizes

See the original size, compressed size, and percentage saved side by side. Download your compressed PDF instantly — no account, no email needed.

Why Use Our PDF Compressor?

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100% Private & Secure

Your PDF files never leave your device. All compression is done locally using WebAssembly in your browser — zero server uploads, zero data stored anywhere.

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3 Compression Levels

Low compression preserves near-original quality with mild size reduction. Medium balances file size and readability. High achieves maximum size reduction for quick sharing.

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Size Comparison

After compression, see your original file size, compressed file size, and exact percentage saved in a clear results panel before downloading.

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Real-Time Progress

A live progress bar tracks each page as it is processed. For large PDFs, you can see exactly how far along compression is in real time.

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Email-Ready PDFs

Reduce a 20MB PDF to under 2MB for email attachments. Great for sending scanned documents, presentations, and portfolios within file size limits.

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Works on Any Device

Fully responsive and touch-friendly. Compress PDFs on Windows, Mac, iPhone, or Android without installing any software.

Popular Use Cases

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Email Attachments

Reduce a large PDF to fit within Gmail, Outlook, or corporate email attachment limits.

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Mobile Sharing

Shrink PDFs to a fraction of their size for sharing via WhatsApp, Telegram, or iMessage.

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Cloud Storage

Compress archives of scanned documents to save storage space on Google Drive or Dropbox.

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Web Uploads

Reduce PDF size for faster web upload speeds and lower hosting bandwidth usage.

Compress PDF – Frequently Asked Questions

The reduction depends on the PDF content and compression level. PDFs with many high-resolution images typically compress 50–80% on High setting. Text-heavy PDFs with few images see smaller reductions (10–30%) because the pages contain less visual data to compress.

Compress PDF Online — Reduce File Size for Free

Our free PDF compressor lets you reduce the size of any PDF document right in your browser — no Acrobat, no server uploads, no account. Whether you need to shrink a PDF for email, reduce storage usage, or optimize documents for web upload, three compression levels give you control over the quality/size trade-off.

All compression happens locally — your files never leave your browser. This makes it completely safe for sensitive PDFs including contracts, medical documents, and financial reports.

How PDF Compression Works

Our tool uses pdfjs-dist to render each PDF page to an HTML5 canvas at a reduced scale, then encodes the canvas as a JPEG image at your chosen quality level. These compressed images are embedded into a new PDF document using pdf-lib. The result is a significantly smaller file where large embedded images and high-resolution content have been downsampled.

This approach works best on PDFs with significant image content — scanned documents, photo portfolios, and presentation PDFs see the largest size reductions. Pure text documents see smaller reductions since the original content is already efficient.

Related PDF Tools

Need to reorganize your PDFs before compressing? Merge PDF combines multiple PDFs into one file, and Split PDF extracts specific pages. All tools are free, private, and run entirely in your browser with no software installation needed.