Compress PDF Online to Reduce File Size

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Compress PDF files online with DocuSwift. Reduce the size of suitable PDF documents, make files easier to share, and download an optimized or compressed version directly to your device.

Large PDF files can be inconvenient to email, upload to websites, or share with colleagues. Documents containing high-resolution images and scanned pages can take up considerable storage space, even when the content itself is relatively short.

A PDF compression tool can help reduce file size. The best method depends on the document: some PDFs benefit from structural optimization, while image-heavy documents may become smaller when their pages are converted to compressed images. These methods have different effects on quality and editability.

What you can do with DocuSwift

• Upload a PDF using the file picker or drag-and-drop.
• Try a structural optimization that retains PDF page content.
• Choose a stronger, image-based compression option.
• Compare the original and resulting file sizes.
• See the actual size difference after processing.
• Download the resulting PDF directly to your device.
• Process supported files locally in your browser.

Easy to useChoose a PDF and a compression method.

Size comparisonSee the actual output size.

Browser-basedNo desktop installation required.

Free Online PDF Compressor

Choose a PDF and select a compression method. The tool measures the actual output size so you can determine whether compression helped your document.

PDF ↓

Compress PDF

Optimize your document and compare the result.

＋ Choose a PDF File Or drag and drop your PDF here PDF only · Maximum 15 MB · Up to 50 pages

Choose a PDF file to get started.

How to Compress a PDF Online

Step 1: Select your PDF

Click the upload area or drag a PDF file from your device into the tool. The page checks whether the file can be opened and how many pages it contains.

Step 2: Choose a compression method

Use Standard optimization if you want to retain the PDF's page content. Choose Stronger image compression if reducing the size of an image-heavy document is more important than retaining selectable text.

Step 3: Adjust image quality if needed

In image mode, select a quality setting. Lower quality can produce smaller files, but fine details, small text, and photographs may become less clear.

Step 4: Start compression

Click Compress PDF and wait for processing to finish. The time required depends on the page count, image content, and capabilities of your device.

Step 5: Compare the results

Review the original size, output size, and reported size change. A PDF may become smaller, remain nearly the same size, or grow after processing.

Step 6: Download and review the file

Download the resulting PDF and open it to check text, page orientation, images, and overall readability before sharing it.

Understanding PDF Compression Methods

PDF compression can work in different ways. Choosing the appropriate method depends on the content and how the document will be used.

Standard structural optimization

This method reads and rebuilds the PDF structure. It can remove some unnecessary structural overhead, but it does not systematically downsample existing images or recompress every embedded image. Consequently, it may produce little or no size reduction.

Image-based compression

This method renders each page as an image and places the compressed image into a new PDF. It can be useful for scanned documents or image-heavy files, but it changes the nature of the document.

• Text is no longer directly selectable or searchable.
• Links, forms, bookmarks, and interactive elements are not retained as working PDF features.
• Digital signatures and other document-level features are not preserved as valid originals.
• Small text may become harder to read, depending on image quality and rendering resolution.

Important: Image-based compression is not suitable for every document. If you need searchable text, accessible content, editable forms, or valid digital signatures, keep the original and use a specialized PDF optimizer that preserves those features.

Tips for Reducing PDF File Size

Review embedded images

High-resolution photographs and scanned pages can contribute significantly to PDF size. If the document is image-heavy, an image-aware PDF optimizer may be more effective than structural optimization alone.

Choose a suitable image quality

For documents intended for screen viewing, moderate image compression may be sufficient. For print-ready materials, preserve a higher-quality original and check the output carefully.

Avoid repeated conversions

Repeatedly rendering pages into compressed images can introduce additional quality loss. Keep the original PDF and compress from that source when you need to try a different setting.

Check the required upload limit

If you need to submit a PDF to a website, check the site's maximum file size before compressing. Aim to meet the required limit while maintaining acceptable readability.

Verify the final document

Open the compressed file and review every page that contains small text, diagrams, tables, or other important details. Compare it with the original before sending it to someone else.

When Should You Compress a PDF?

• Email attachments: Reduce file size when an email service has an attachment limit.
• Online submissions: Prepare documents for upload when a portal specifies a maximum file size.
• Digital archiving: Reduce storage needs when the chosen compression method is appropriate for long-term records.
• Document sharing: Make suitable files easier to transfer or store.

Compression is not always the best solution. For legal, financial, academic, or archival documents, retain the original and verify that the output meets the relevant quality and preservation requirements.

Privacy and Document Security

PDFs may contain personal information, financial records, contracts, or confidential business materials. Consider how your documents are handled before using any online tool.

This compressor processes selected PDF files locally in your browser and does not intentionally upload them to a DocuSwift processing server. The page loads its PDF and document-generation libraries from external content delivery networks. Ordinary website requests may also occur.

• Only process documents you are authorized to use.
• Avoid handling sensitive documents on shared or public computers.
• Keep a backup of your original PDF.
• Inspect the compressed file before sharing it.
• For highly confidential documents, consider an approved offline PDF application.

Frequently Asked Questions

Is this PDF compressor free?

Yes. The tool on this page has no payment step built into its code. It runs in your browser and requires JavaScript.

Will compressing a PDF always reduce its size?

No. The result depends on the PDF's structure and content. Structural optimization may provide little reduction, while image-based compression can reduce some image-heavy files but may also produce a larger file in certain cases.

What is the difference between standard and image compression?

Standard optimization rebuilds the PDF structure and generally retains selectable page content. Image compression converts each page into a JPEG image, which can reduce size but removes directly selectable text and interactive PDF features.

Can I compress a scanned PDF?

Scanned PDFs often contain page images. Image-based compression may reduce their size, but it does not create searchable text. OCR is needed if you want text recognition.

Will my text remain selectable?

In Standard optimization mode, selectable text is generally retained. In image-based mode, pages become images, so the text is no longer directly selectable or searchable.

Are my files uploaded to a server?

The compression code processes the selected PDF locally in your browser and does not intentionally send it to a DocuSwift processing server. External JavaScript libraries are loaded to provide the functionality.

Why did the output become larger?

Rebuilding a PDF can add structural overhead, and converting pages into images can be inefficient for documents that already contain optimized text or graphics. Compare the actual output size and keep the original if the result is not useful.

Can I use the tool on my phone?

Modern mobile browsers may support the tool, but processing multiple high-resolution pages can require substantial memory. A desktop browser may be more convenient for large documents.

Compress PDF Files with DocuSwift

DocuSwift helps you experiment with PDF optimization and compare the resulting file size. Choose the method that best fits your document, review the actual results, and download the output when it meets your needs.

For the best experience, keep a copy of your original document and check the compressed PDF carefully before sharing, printing, or submitting it.

Disclaimer: Compression results vary with the source PDF, its structure, page content, browser capabilities, and available memory. No particular reduction in file size or preservation of all document features is guaranteed.