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PDF Compressor – Compress PDF Online Free

Compress PDF files instantly without losing quality. Learn how to compress a PDF, reduce PDF file size for email or web upload, and choose from 4 quality presets Screen, eBook, Printer, or Prepress. Works on Windows, Mac, and mobile. 100% free, no registration.

Instant Compression Quality Presets Free & Secure

What Is PDF Compression?

PDF compression reduces the file size of a PDF document by optimizing embedded images, fonts, and internal structure without changing the visible content. A compressed PDF is easier to email, upload, or store, and often opens faster on slow connections.

Our free online PDF compressor uses a professional optimization engine compiled to WebAssembly (WASM) that runs entirely in your browser. That means you can compress a PDF online free no uploads, no waiting, no registration and your files never leave your device.

When Should You Compress a PDF?

  • Email attachments that exceed Gmail, Outlook, or Yahoo size limits (usually 20–25MB)
  • Uploading documents to government, university, or job portals with size caps (often 2–10MB)
  • Sharing scanned PDFs or image-heavy presentations on WhatsApp, Telegram, or Slack
  • Saving storage space on your phone, laptop, or cloud drive
  • Making PDFs load faster on websites and mobile devices

Key Features

Advanced Compression Engine

Industry-standard PDF optimization running locally in your browser via WebAssembly. Desktop-grade compression quality with complete privacy.

4 Quality Presets

Choose from Screen (smallest), eBook (balanced), Printer (high quality), or Prepress (maximum quality). Find the perfect balance between size and quality.

Size Savings Display

See exactly how much space you saved with before/after file size comparison and percentage reduction. Know your compression results instantly.

100% Browser-Based

All compression happens locally in your browser. Your PDF files are never uploaded to any server. Complete privacy and security guaranteed.

Progress Tracking

Real-time progress bar shows compression status from file reading through compression to completion. Never wonder if it's still working.

Up to 100MB Files

Compress PDFs up to 100MB in size. Handles large documents, presentations, ebooks, and scanned files with ease. Optimized for memory efficiency.

How to Compress a PDF

1
Upload PDF

Drag & drop your PDF file or click to browse. Supports files up to 100MB. Only one file at a time for optimal compression.

2
Choose Quality

Select from 4 presets: Screen (72 DPI), eBook (150 DPI), Printer (300 DPI), or Prepress (maximum quality). Higher quality = larger file.

3
Compress

Click "Compress PDF" to start. The compression engine processes your file locally with real-time progress tracking.

4
Download

See the size reduction percentage and download your compressed PDF. Compare original vs compressed file sizes instantly.

How to Compress a PDF on Mac, Windows, and Mobile

The easiest way to compress a PDF on any device is to use our free browser-based tool it works the same on Mac, Windows, Linux, iPhone, iPad, and Android. Just open this page, drop your PDF, pick a quality preset, and download the smaller file. No app installation required.

Compress PDF on Mac

On macOS, you can also use Preview (File → Export → Quartz Filter → Reduce File Size), but results are limited. Our online compressor gives you 4 quality levels and typically achieves 60–80% reduction far better than Preview's default. Works on Intel and Apple Silicon Macs.

Compress PDF on Windows

Windows doesn't include a built-in PDF compressor. Adobe Acrobat Pro has one, but it's paid. Our free tool runs in any browser (Chrome, Edge, Firefox, Brave) and handles files up to 100MB no Adobe subscription needed.

Compress PDF on Mobile

On iPhone, iPad, or Android, just open this page in Safari or Chrome. Tap "Select PDF File," choose your file, and compress. Large files (50MB+) may take 30–60 seconds on mobile due to CPU limits for best results, use a desktop for big documents.

How to Compress a PDF with Adobe Acrobat

Adobe Acrobat Pro DC includes a PDF optimizer (File → Save As Other → Optimized PDF), and Adobe Acrobat Online offers a free web compressor with a file size limit. If you're looking for a free Adobe Acrobat alternative that doesn't require a subscription, our tool gives you the same 4 quality presets (Screen, eBook, Printer, Prepress) with no sign-up.

Adobe Acrobat Pro DC (Desktop)

Open your PDF in Acrobat Pro → File → Save As Other → Optimized PDF → choose "Standard" or "Minimum" preset. Acrobat Pro is paid ($12.99–$24.99/month).

Adobe Acrobat Online (Web)

Adobe's free online compressor works but limits file size and requires an Adobe account. Our tool handles up to 100MB with no account.

Adobe Reader (Free)

Adobe Reader cannot compress PDFs it's a viewer only. You need Acrobat Pro or a third-party tool. Our free compressor fills that gap.

How We Compare to Other PDF Compressors

Looking for a free alternative to iLovePDF, Smallpdf, or Adobe Acrobat? Here's how our browser-based compressor stacks up:

FeatureOnlineOCR.ioiLovePDFSmallpdfAdobe Acrobat
PriceFreeFree w/ limitsFree w/ limitsPaid
RegistrationNot requiredRequired for someRequired for someRequired
File upload to serverNeverYesYesYes
Max file size100MBVariesVariesVaries
Quality presets4113
Works offlineYes (after load)NoNoNo

Comparison based on publicly available information as of 2026. Trademarks belong to their respective owners.

Why Choose Our PDF Compressor?

  • No Registration Required - Start compressing PDFs immediately
  • WebAssembly Engine - Desktop-grade compression in browser
  • 4 Quality Levels - Screen, eBook, Printer, and Prepress presets
  • Up to 100MB - Handle large PDF documents with ease
  • 100% Browser-Based - Files never leave your device
  • Real-Time Progress - See compression status as it happens
  • Size Comparison - Before/after with percentage savings
  • Memory Efficient - Optimized for large file processing

Frequently Asked Questions

Our tool uses a professional PDF optimization engine compiled to WebAssembly (WASM) running directly in your browser. It optimizes images, fonts, and PDF structure based on your chosen quality preset. Screen (72 DPI) produces the smallest files, eBook (150 DPI) balances quality and size, Printer (300 DPI) maintains high quality, and Prepress preserves maximum quality.

Screen (72 DPI): Best for email attachments and web sharing. Smallest file size.

eBook (150 DPI): Good balance for digital documents and e-readers.

Printer (300 DPI): High quality for printing and professional use.

Prepress: Maximum quality preservation for commercial printing.

Yes! All compression happens entirely in your browser using WebAssembly. Your PDF files are never uploaded to any server. The compression engine runs locally on your device. We cannot see, access, or store your files. Your documents remain completely private.

The tool supports PDF files up to 100MB in size. For best performance with large files, we recommend using the Screen or eBook quality presets which process faster. The compression engine is optimized for memory efficiency to handle large documents smoothly.

Size reduction depends on the original PDF content and chosen quality preset. Screen quality typically achieves 60-80% reduction for image-heavy PDFs. Text-based PDFs may see smaller reductions. After compression, you'll see the exact before/after sizes and percentage saved.

Compression time varies based on file size, content complexity, and your device's processing power. Small files (under 10MB) typically compress in seconds. Larger files (50-100MB) may take 30-60 seconds. The real-time progress bar keeps you informed throughout the process.

Quality impact depends on the preset you choose. Prepress and Printer maintain near-original quality. eBook provides a good balance. Screen quality reduces image resolution significantly for maximum size savings. Text content remains sharp at all quality levels.

Yes! Our PDF Compressor is fully responsive and works on all devices. However, compression is CPU-intensive and works best on desktop. Mobile devices can compress smaller files, but larger files may take longer due to processing limitations.

The easiest way to compress a PDF on Mac is to use our free browser-based tool it works in Safari, Chrome, Firefox, or Edge on any macOS version. Alternatively, Mac's built-in Preview app can reduce file size via File → Export → Quartz Filter → Reduce File Size, but results are limited. Our tool gives you 4 quality presets and typically achieves 60–80% reduction for image-heavy PDFs.

Windows doesn't include a built-in PDF compressor. You can use Adobe Acrobat Pro (paid), Microsoft Word (export as PDF with reduced quality limited), or our free online tool. Our compressor runs in any modern browser (Chrome, Edge, Firefox, Brave) and handles files up to 100MB with no installation or subscription.

In Adobe Acrobat Pro DC: open your PDF, go to File → Save As Other → Optimized PDF, and choose a preset (Standard or Minimum). In Adobe Acrobat Online: upload your PDF and use the "Compress PDF" tool (free with account, file size limits apply). Adobe Reader cannot compress PDFs it's a viewer only. If you want a free alternative without an Adobe account, use our tool above.

If you need to combine multiple PDFs into a single file and compress the result, first use our Merge PDF tool to join them, then run the merged file through this compressor. You can also compress each PDF individually first (smaller individual files) and then merge them.

Para comprimir un PDF gratis: arrastra tu archivo PDF a la zona de carga, elige una calidad (Screen, eBook, Printer o Prepress), haz clic en "Compress PDF" y descarga el archivo comprimido. Todo el procesamiento ocurre en tu navegador tus archivos nunca se suben a ningún servidor. Funciona en Windows, Mac, iPhone, iPad y Android.

Our PDF compressor is 100% free no hidden fees, no daily limits, no registration, and no watermarks. Just open this page, drop your PDF, choose a preset, and download. Unlike iLovePDF or Smallpdf, we don't upload your files to a server, so you also get complete privacy. Compress as many PDFs as you want, whenever you want.

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