UFOZoo

Compress PDF — Reduce PDF File Size Online for Free

Compress PDF files online without losing readability. Shrink scanned documents and image-heavy PDFs for email and sharing. No upload, 100% browser-based.

Features

  • ✓Compress scanned PDFs: every page is re-encoded as an optimized JPEG, which removes redundant image data for the biggest savings
  • ✓Shrink large PDFs for email: reduce multi-megabyte documents down to attachment-friendly sizes under typical 10 MB limits
  • ✓Three compression levels: High (quality 0.85), Medium (quality 0.6) and Low (quality 0.35) presets for different needs
  • ✓Smart strategy selection: compares page re-encoding against a lossless PDF rewrite and automatically keeps the smaller result
  • ✓Text and vector PDFs stay crisp: pure text or vector pages are safely rewritten without rasterization, so text remains selectable
  • ✓Preserves page size and count: every page of the original document is kept at the same dimensions and order
  • ✓Page-by-page progress: watch exactly where the process is, page by page, even on documents with hundreds of pages
  • ✓No watermark, no page limit: compress documents of any length for free, with nothing stamped onto your pages
  • ✓Instant size comparison: see the original size, the new size and the exact percentage saved before you save the file
  • ✓100% in-browser processing: your PDF never leaves your device, making it safe for contracts, IDs and medical documents
  • ✓Works offline: the entire tool runs client-side with zero server requests, so it works even with no internet connection
  • ✓Free with no sign-up: no accounts, no quotas, no file-size caps, and no hidden fees

How to Use

  1. 1Open the PDF you want to compress by clicking the open area or dragging and dropping the file onto it
  2. 2Review the original file size and page count that are shown as soon as the document loads
  3. 3Pick a compression level: High keeps the best quality, Medium balances quality and size, Low produces the smallest file
  4. 4Click Compress PDF and wait: for large documents, progress is shown page by page
  5. 5Compare the original and compressed sizes along with the exact percentage saved
  6. 6Click Save PDF to store the compressed file on your device, keeping the original untouched
  7. 7For scanned or image-heavy PDFs, choose Medium or Low: re-encoding removes redundant image data for the largest savings
  8. 8For text-only PDFs, any level works: the tool detects that re-encoding would not help and applies a safe rewrite instead
  9. 9Compressing a PDF for email? Use Low and aim for under 10 MB so the file fits common attachment limits
  10. 10Need to keep print quality? Use High: pages keep their resolution while the file still becomes noticeably smaller

Frequently Asked Questions

How much can I compress a PDF?

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Savings depend on the content. Scanned and image-heavy PDFs typically shrink by 50-80%, while text-heavy PDFs often shrink by 10-40%. The tool always compares both compression strategies and keeps the smaller output, so you get the best possible result for your file.

Is there a difference between compressing text PDFs and scanned PDFs?

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Yes. Scanned PDFs are built from large images, so re-encoding every page as an optimized JPEG removes most of the weight. Text and vector PDFs contain fonts and paths that do not rasterize well, so the tool applies a lossless rewrite that strips redundant objects instead: the text stays crisp and searchable.

What do the High, Medium and Low levels mean?

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They map to JPEG quality values of 0.85, 0.6 and 0.35 used when re-encoding pages. High looks nearly identical to the original, Medium is a balanced default for most documents, and Low produces the smallest file: ideal for email attachments or long-term archiving where slight softening is acceptable.

Will my text remain readable and searchable?

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For scanned documents, yes: the text is part of the image and stays fully readable. For text-based PDFs, the tool's rewrite strategy preserves the original text layer, so words remain selectable and searchable. Page re-encoding is only kept when it produces a smaller file than the rewrite.

Why didn't my PDF get smaller?

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Some files are already well optimized: PDFs created from compressed images, small text-only documents, or files previously compressed with another tool often cannot shrink further. In that case the tool shows a notice and lets you save the cleaned-up rewrite anyway.

Is it safe to compress confidential documents?

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Completely. All processing happens inside your browser using JavaScript: your file is never uploaded to any server. This makes the tool safe for contracts, tax documents, medical records and other sensitive PDFs, and it even works while you are offline.

Can I compress a scanned PDF?

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Yes, and it is where the tool shines. Scanned pages are stored as large uncompressed or lightly compressed images, so rendering each page and re-encoding it as a tuned JPEG routinely cuts file size by half or more while keeping text fully legible.

Which compression level should I choose?

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Use High for documents that will be printed or read carefully on screen, Medium for everyday sharing where quality still matters, and Low for emails, uploads or archives where size is the priority. When in doubt, start with Medium and check the preview sizes.

Is there a limit on file size or number of pages?

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There is no artificial limit. The only constraint is your device's memory: very large PDFs with hundreds of pages are processed page by page, so memory usage stays bounded and progress is shown throughout.

Will the page size and layout stay the same?

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Yes. Every page keeps its original dimensions and order, and each page is rendered at the same aspect ratio. The compression affects image encoding only, so nothing is cropped, rotated or reflowed.

What happens to bookmarks, links and metadata?

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The re-encoded output is rebuilt from the rendered pages, so interactive features such as links and bookmarks are not carried over. When the rewrite strategy wins, the document structure and metadata are preserved. For heavily interactive PDFs, consider using High so the rewrite is more likely to be selected.

How do I compress a PDF for email?

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Select the file, choose the Low level, click Compress PDF and save the result. The percentage indicator tells you when the file drops below common attachment limits such as 10 MB, and the tool shows the final size before you save.

Does the tool work on mobile?

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Yes. The interface is fully responsive and works in mobile browsers: open the PDF from your files app, compress it, and save the result to your device. Because everything runs locally, there is no upload bandwidth to worry about.

Is this tool really free?

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Yes: free, with no sign-up, no watermark, no daily quota and no hidden premium tier. Running the compression entirely in your browser also means there are no server costs behind the scenes, which is what keeps the tool free.

Can I compress a PDF to a specific size?

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There is no exact target-size mode, but the Low level usually shrinks scanned PDFs below common email attachment limits (10 MB or 1 MB). After compressing, check the new size in the result panel; if it is still too large, pick Low and compress again.

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