Compress PDF

Compress PDF files online for free. Reduce file size by optimizing images and removing unused data. No upload to any server — everything runs privately in your browser.

Drop a PDF here or click to upload

PDF files of any size

What Is the PDF Compressor?

The PDF Compressor reduces your PDF file size directly in your browser. Upload any PDF, choose a compression quality preset, and download a smaller version. The tool re-encodes embedded images at lower quality and strips unnecessary metadata and unused internal objects. No server upload, no signup, completely private.

How to Compress a PDF

  • Upload a PDF by clicking the upload area or dragging and dropping.
  • Choose a quality preset: Low for maximum compression, Medium for balanced results, or High to preserve the most quality.
  • Wait for the compression to finish — progress is shown in real time.
  • Review the before and after file sizes and the compression ratio.
  • Download your compressed PDF.

Tips for Best Results

  • Image-heavy PDFs (scanned documents, photo reports) benefit the most from compression.
  • The Medium preset is a great starting point — it offers a strong balance between quality and file size.
  • If the compressed file is barely smaller, the PDF likely has little image content and is already optimized.
  • Try different presets to find the right quality-to-size ratio for your needs.
  • Large PDFs may take a few seconds to process — the tool shows progress while working.

How the Compression Works

The tool uses pdf-lib to parse the PDF structure, then iterates through every page to find embedded raster images. Each image is decoded, drawn onto an HTML5 Canvas, and re-encoded as a JPEG at the chosen quality level. The compressed image replaces the original only if it is smaller. Additionally, all pages are copied into a fresh PDF document, which automatically removes unused objects, orphaned data, and document metadata — reducing size even for text-only PDFs.

Frequently Asked Questions

How does the PDF compressor work?+
The tool loads your PDF in the browser using pdf-lib, then iterates through each page looking for embedded images. Images are re-encoded at lower quality using the HTML5 Canvas API. The tool also strips unnecessary metadata and unused objects by copying pages into a fresh PDF document, which removes bloat accumulated from edits.
Is my PDF uploaded to a server?+
No. All compression happens entirely in your browser using JavaScript. Your PDF never leaves your device, making it completely private and secure. There are no file size limits imposed by a server, only your browser's available memory.
How much can I reduce my PDF file size?+
It depends on the PDF content. Image-heavy PDFs (scanned documents, photo-rich reports) can often be reduced by 50-80% at medium quality. Text-heavy PDFs with few images may only shrink by 10-30% since text is already compact. The tool shows you the exact savings before you download.
Will compressing my PDF reduce its quality?+
Text, vector graphics, and annotations remain untouched — only embedded images are re-encoded at lower quality. At the 'High' preset, most images look virtually identical to the originals. The 'Medium' preset offers a good balance, while 'Low' maximizes compression with more noticeable quality reduction in images.
What types of PDFs work best with this tool?+
PDFs with large embedded images — scanned documents, photography portfolios, marketing brochures, and presentation exports — see the biggest reductions. PDFs that are mostly text or vector graphics are already quite compact and will see smaller improvements.
Can I compress password-protected PDFs?+
The tool can handle PDFs that are not encrypted. If your PDF requires a password to open, you'll need to remove the password protection first. PDFs with only print/edit restrictions (owner password) may still work depending on the encryption level.
Does compression remove any content from my PDF?+
No pages or visible content are removed. The tool only reduces image quality based on your chosen preset, strips document metadata (author, creation date, etc.), and removes unused internal objects. All pages, text, links, and annotations are preserved.

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