100% In-Browser Privacy • Zero Server Uploads • No File Limits

Compress PDF Files

Shrink large PDF documents in seconds to bypass email caps and application portal limits. Processed 100% locally on your computer with zero file uploads or tracking.

Don't have a PDF ready?
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Email Attachment Caps

Bypass strict 20MB or 25MB attachment ceilings on Gmail, Outlook, and corporate Exchange mailboxes with one click.

Bypass Email Limits
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Government & Job Portals

Satisfy rigid 1MB, 2MB, or 5MB file restrictions when submitting tax filings, visa paperwork, resumes, and university admissions.

Application Ready
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Scanned Receipt Bloat

Office scanners often create massive 30MB PDFs for simple paper pages. Re-sample them into lightweight documents under 500KB.

Scanner Optimization
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100% Client-Side Privacy

Never upload private bank statements, NDA contracts, or medical records to anonymous third-party servers. All processing stays in RAM.

Local Device Execution

📋 How to Compress a PDF in Your Browser

  1. 1
    Select or Drop Your PDF Drop your document into the upload area or click to browse. Files up to hundreds of megabytes are supported without cloud timeouts.
  2. 2
    Pick a Compression Preset Select Balanced Quality for the optimal compromise between crisp text and file reduction, or Extreme to shrink files to the absolute minimum.
  3. 3
    Click "Compress PDF Now" Watch the real-time progress bar as pages are resampled and repacked using client-side binary streams.
  4. 4
    Download Your Shrunk PDF View the space savings summary and download your newly compressed document instantly.

💡 Tips for Maximum PDF Size Reduction

Use Grayscale for Scanned Documents If your document is primarily black-and-white receipts or typed text, toggle Convert to Grayscale to strip 66% of colour channel data without losing readability.
Why 140 DPI is Ideal for Screens Standard computer displays render at 96–120 DPI. Resampling 300+ DPI images to 140 DPI removes redundant pixels invisible to the naked eye while slashing megabytes.
Combine with Page Removal If your PDF has trailing blank pages or terms sheets, pair this tool with our PDF Organiser to delete unneeded pages first!
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Under the Hood: Binary Stream Quantisation & In-Browser Compression Architecture

PDF.js canvas rasterisation, JPEG DCT quantization, and PDF-Lib binary stream packaging.

Details

The Bottleneck: High-DPI Embedded Rasters

Unlike plain text and vector instructions, embedded raster graphics account for over 90% of a typical PDF's file size. Most office scanners default to uncompressed 300–600 DPI RGB bitmaps, ballooning a 2-page document into tens of megabytes.

Canvas Resampling Pipeline

BWTools uses Mozilla's PDF.js to unpack the PDF's display list and render each sheet onto an HTML5 2D Canvas context at a scaled viewport corresponding to target DPI. The canvas is then encoded to an optimized JPEG stream utilizing Discrete Cosine Transform (DCT) quantization.

PDF-Lib Page Reconstruction

A clean, new PDFDocument instance is instantiated via pdf-lib. Each optimized image is embedded as a native XObject and drawn to match the original page's physical point dimensions (e.g., A4: 595.28 × 841.89 pt), preserving print geometry while shedding gigabytes of redundant image bytes.

❓ Frequently Asked Questions

Will compressing my PDF make the text blurry? ▼

No. The "Balanced Quality" preset uses 140 DPI, which provides super-crisp text on all laptop screens, tablets, and phones. If you need razor-sharp text for printing, choose the "Light Compression (200 DPI)" preset.

Is it safe to compress confidential bank statements or tax returns? ▼

100% yes. Unlike traditional services like Smallpdf or iLovePDF where files are uploaded to remote servers, BWTools executes entirely inside your browser's local sandbox memory. Zero bytes are transmitted across the internet.

How much file size reduction can I expect? ▼

For PDFs containing scanned images, photos, or graphics, size reductions typically range from 50% to over 85%. Documents that are already pure plaintext without images may see smaller reductions since text is already compact.

Are there any limits on page count or document size? ▼

There are no arbitrary file size limits or paywalled page caps. Performance depends purely on your workstation's memory. Even 50+ page documents compress smoothly.