PDF Compressor: Reduce PDF File Size Free

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Reduce the file size of a PDF so it is easier to upload, email or share. Choose how strongly to compress, see the new size before you download, and keep your text sharp. The work is done in your browser.

Drag and drop a PDF here

Choose a PDF

One PDF at a time.

Your PDF is processed in your browser. It is not uploaded to MOCC or to any third-party service. Only the open-source pdf-lib compression library is downloaded, from the cdnjs content delivery network, when you add a file.

How the PDF compressor works

Most of the weight in a scanned or photo-heavy PDF is the pictures inside it. This tool opens your PDF in your browser, finds those pictures, re-encodes them as smaller JPEG images and rebuilds the file in a more compact form. Text and vector drawings are not touched, so they stay sharp and selectable.

• Low keeps the original picture size and lowers JPEG quality a little. Use it when appearance matters most.
• Balanced also reduces very large pictures to a sensible resolution for reading on screen and printing at normal size. It is the best starting point.
• High reduces pictures further for the smallest file. Fine detail and small print in scans can look softer.

What kinds of PDFs compress well?

Scanned documents and PDFs with photographs usually shrink a lot. A PDF that is made only of text and vector graphics is already small, so there is little to remove. In that case the tool tells you so instead of pretending it made a difference, and it never offers a "compressed" file that is not smaller than your original. Pictures stored in formats that are already very efficient, such as black-and-white scans, are left as they are.

Things to know before you compress

• Password-protected PDFs cannot be opened by this tool. Remove the password in a PDF reader first.
• Digitally signed PDFs change when they are rewritten, so a signature on the compressed copy will no longer be valid. Keep the original for anything that must stay signed.
• Always check the result. Use Open to check it before you send the compressed PDF anywhere.
• Very large files can take a while, especially on a phone. Phones accept smaller files than computers.

Keep your documents organised

Compressed and ready? See where the rest of your preparation lives.

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PDF compressor FAQ

Is my PDF uploaded to a server?

No. Your PDF is processed in your browser and is not uploaded to MOCC or to any third-party service. The only thing downloaded is the open-source pdf-lib library that does the work, which is fetched from the cdnjs content delivery network.

Why did my PDF not get smaller?

If the PDF contains mostly text and vector graphics, or its pictures are already highly compressed, there is little to reduce. The tool then says so and does not give you a compressed file. If you used Low or Balanced, you can try a stronger level.

Will the text still be selectable?

Yes. Only the pictures inside the PDF are re-encoded. Text and vector graphics are left unchanged.

Can it compress a password-protected PDF?

No. Remove the password in a PDF reader and try again.

What is the maximum file size?

150 MB on a computer and 40 MB on a phone or tablet. Bigger files are rejected with a message instead of crashing your browser.

Does compression affect a digital signature?

Yes. The compressed copy is a rewritten file, so any digital signature on the original will not be valid on it. Keep the original for signed documents.