How to Use This Tool
Upload Your PDFs
Click the upload area, drag and drop files, or paste from clipboard (Ctrl+V). Accepts PDF files up to 25 MB each, 100 MB total, and up to 10 files at once.
Choose Compression Level
Select Low (best quality, moderate reduction), Medium (balanced - default), or High (smallest file, some quality loss). Enable Grayscale to further reduce size for B&W documents.
Compress
Click Compress or Compress All. Each page is re-rendered at the target resolution and re-encoded as an optimized JPEG. Progress shows which page is being processed for each file.
Review & Download
Each thumbnail shows original and compressed size with the percentage saved. Download a single file directly, or all as a ZIP. If compression would increase file size, the original is kept.
Frequently Asked Questions
Does compression reduce PDF quality?
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It depends on the level you choose. Low compression preserves good visual quality (JPEG 70%, 150 DPI). Medium is balanced (50%, 110 DPI). High gives the smallest file with noticeable quality loss (30%, 72 DPI). Text-only PDFs see minimal quality change at any level.
Is my PDF uploaded to a server?
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No. This tool runs 100% in your browser. Your PDFs never leave your device. All rendering, image encoding, and PDF rebuilding happens locally. No data is transmitted, no cookies are used, and no third-party services have access to your files.
What is the maximum file size?
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Each file can be up to 25 MB, with a total limit of 100 MB across all uploaded files. You can upload up to 10 PDFs at once.
Why did my file size not change?
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If the tool determines that compression would produce a larger file than the original, it automatically keeps the original. This can happen with PDFs that are already well-optimized or text-only. The thumbnail will show 0% change in this case.
How does the compression work?
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Each page is rendered at the target resolution, then re-encoded as an optimized JPEG image. The PDF is rebuilt from these compressed page images. Metadata, JavaScript, embedded thumbnails, and XMP streams are also stripped. This is the same approach used by professional PDF compression tools.
What is the Grayscale option for?
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Enabling Grayscale converts all pages to black and white before compression. This further reduces file size and is ideal for scanned documents, text-heavy PDFs, or any document that doesn't need color.
Can I compress password-protected PDFs?
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The tool attempts to load encrypted PDFs. If the PDF requires a password to open, compression may fail. PDFs with owner-level restrictions (print/copy disabled) are usually processed successfully.
How does batch compression work?
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Upload up to 10 PDFs at once via drag and drop, file picker, or clipboard paste. Click Compress All to process every file sequentially. Each thumbnail shows its own progress spinner with page-level status. Download all compressed files as a single ZIP archive.
What Is Compress PDF?
Compress PDF is a free browser-based tool that significantly reduces PDF file size by re-rendering each page at an optimized resolution and re-encoding images as compressed JPEGs. Choose from three compression levels - Low, Medium, or High - to balance quality and file size. Enable Grayscale for additional savings on B&W documents.
Everything runs 100% in your browser using a background Web Worker, so the UI stays responsive even with large files. Your PDFs are never uploaded to any server. You can compress multiple files at once, compare original and compressed sizes, and download results individually or as a ZIP archive.
Features Explained
Image Recompression
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The core compression technique. Each page is rendered at the target resolution using a built-in PDF renderer and re-encoded as an optimized JPEG. This dramatically reduces file size - especially for image-heavy PDFs, scanned documents, and presentations. Typical reduction: 40-85%.
Compression Presets
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Three presets control the quality-size tradeoff. Low compression (JPEG 70%, 150 DPI) preserves good quality with solid reduction. Medium (50%, 110 DPI) is the default balanced option. High (30%, 72 DPI) produces the smallest files for maximum compression.
Grayscale Conversion
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Enable the Grayscale option to convert all pages to black and white before compression. This removes color data entirely, further reducing file size. Ideal for scanned documents, text-heavy PDFs, or any document that doesn't need color.
Metadata & Cleanup
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Strips author, title, subject, keywords, producer, creator, XMP metadata streams, embedded JavaScript, file attachments, and page thumbnails. This reduces file size and protects your privacy.
Background Processing
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Compression runs in a Web Worker thread, keeping the browser responsive even with large files. Each file shows page-level progress so you can track exactly where it is in the process.
Batch Processing
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Upload and compress up to 10 PDFs at once. Each file is processed sequentially with its own progress indicator. Download all compressed files as a single ZIP archive.
Smart Size Check
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If compression would produce a file larger than the original, the tool automatically keeps the original. You never end up with a bigger file than you started with.
ZIP Download
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When compressing multiple PDFs, download all results as a single ZIP archive. Each file inside is named with a -compressed suffix for easy identification.
Clipboard Paste
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Press Ctrl+V to paste a PDF directly from your clipboard. Useful for quickly compressing downloaded documents without navigating to a file picker.
Who Is This Tool For?
Students
Compress lecture notes, assignments, and research papers before submitting to online portals with strict file size limits.
Teachers & Professors
Shrink course materials, syllabi, and handouts before uploading to Google Classroom, Canvas, or Moodle.
Office Workers
Reduce PDF sizes for email attachments that bounce due to size limits. Compress reports, invoices, and presentations.
Freelancers
Compress contracts, proposals, and deliverables before sending to clients via email or project management tools.
Lawyers & Legal Professionals
Reduce the size of legal filings, contracts, and case documents that need to meet court e-filing size limits.
Accountants
Compress financial reports, tax documents, and audit files before sharing with clients or uploading to portals.
Real Estate Agents
Shrink property brochures, listing agreements, and disclosure documents for fast email delivery.
HR Professionals
Compress resumes, offer letters, and policy documents before uploading to applicant tracking systems.
Healthcare Workers
Reduce the size of medical records, reports, and referral documents for electronic health record systems.
Architects & Engineers
Compress drawings, specifications, and project documentation for sharing via collaboration platforms.
Small Business Owners
Compress invoices, receipts, and business plans for email and cloud storage without paying for extra space.
Government Workers
Meet file size requirements for public-facing portals and internal document management systems.
Researchers
Compress journal papers, datasets, and grant applications before uploading to submission portals with strict size limits.
Insurance Agents
Shrink claim forms, policy documents, and supporting evidence files for faster processing through digital systems.
Nonprofit Workers
Compress grant applications, annual reports, and donor communications when working with limited hosting and email capacity.
Bankers & Finance Pros
Reduce the size of loan applications, financial statements, and compliance documents for secure digital submission.
Journalists
Compress press releases, interview transcripts, and editorial documents before sharing with editors and publishers.
Paralegals
Compress massive case files, depositions, and court filings that need to meet strict e-filing size limits.
Consultants
Compress client deliverables, strategy decks, and audit reports before sharing through project management platforms.
Tax Preparers
Compress tax returns, W-2s, and supporting documents before uploading to IRS e-file systems and client portals.
Authors & Writers
Compress manuscript drafts, book proposals, and galley proofs before sending to agents and publishers.
Loan Officers
Compress mortgage applications, appraisals, and closing documents that are notoriously large for digital submission.
Procurement Officers
Compress RFPs, bid documents, and vendor agreements for uploading to procurement management systems.
Administrative Assistants
Compress and email PDFs daily - reports, memos, and scanned documents that need to fit within inbox size limits.
Tips for Compressing PDFs
Start with Medium compression
Medium is the best default for most documents - it achieves 40-70% reduction while keeping text readable and images clear. Switch to High only if you need the absolute smallest file.
Use High for email attachments
Many email providers limit attachments to 10-25 MB. High compression can shrink a 20 MB PDF to 3-5 MB, easily fitting within limits.
Enable Grayscale for B&W documents
If your PDF is a scanned document, text-heavy report, or doesn't need color, enabling Grayscale removes all color data and can cut file size significantly beyond the preset alone.
Use batch mode for bulk work
Upload up to 10 PDFs at once (25 MB each, 100 MB total) and compress them in a single pass. Download the ZIP to get every file in one click.
Image-heavy PDFs compress the most
Scanned documents, presentations, and PDFs with photos see the largest reductions (60-85%). Text-only PDFs compress less since there are fewer images to optimize.
Original is kept when compression doesn't help
The tool automatically keeps the original file if compression produces a larger result. You never need to worry about accidentally increasing file size.
Privacy & Security
Your files never leave your device
This tool processes PDFs entirely in your browser using JavaScript. No files are uploaded to any server. No data is transmitted over the internet. No cookies or tracking are used. Your documents remain completely private and secure on your device at all times.