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How to Compress a PDF

Your PDF is too big. Maybe it is a scanned document at 50MB, a design file loaded with images, or a report generated from software that does not optimize file size. Whatever the reason, you need it smaller — for email, for upload, or just for sanity.

KuroPDF gives you two compression modes: quality-based (reduce image quality across the board) and target-size (specify exactly how small you need the output). Both run locally in your browser, so sensitive documents like tax returns and medical records never leave your device.

The engine works by identifying and recompressing the embedded images inside your PDF. Text and vector graphics (charts, logos, line art) remain untouched — they are already small and do not benefit from lossy compression. This means your compressed PDF still has selectable, searchable text.

Open the Compress PDF tool →
  • Files never leave your device
  • No size limits
  • Free, no sign-up

How to how to compress a pdf

  1. 1
    Load your PDF

    Drop the oversized PDF into the Compress PDF tool. It is parsed locally — your document never leaves your device.

  2. 2
    Choose your compression mode

    Quality mode: pick a quality percentage (lower = smaller). Target-size mode: enter the exact size you need (e.g., 5MB for email, 1MB for a form upload).

  3. 3
    Compress

    Click compress. The engine iterates through quality levels until the file meets your target. A progress bar shows the status for large documents.

  4. 4
    Download the result

    The compressed PDF downloads with one click. Text remains selectable and sharp. Compare the file sizes to see the reduction.

Frequently asked questions

How much can a PDF be compressed?

It depends on the content. Scanned documents (page-sized images) compress dramatically — often 80-90% reduction. Text-heavy PDFs with few images may only shrink 10-20% because text is already tiny.

Will text still be searchable after compression?

Yes. The engine only recompresses embedded images. Text, vector graphics, annotations, and form fields are preserved as-is.

What is the difference between quality mode and target-size mode?

Quality mode applies a fixed compression level to all images — simple and fast. Target-size mode iterates, testing different quality levels until the output hits your specified size — slower but guarantees the result fits.

Is it safe for confidential documents?

Everything runs locally in your browser using WebAssembly. Because no data is uploaded to a cloud server, your files remain strictly private, and the entire process generates zero server carbon emissions, making it highly eco-friendly.

Why is my text-only PDF not getting smaller?

Text in a PDF is already extremely compact (just character codes and positions). If your PDF has no embedded images, there is very little that lossy compression can do. Try the Optimize PDF tool instead for lossless structural cleanup.

Can I compress a scanned PDF without losing readability?

Yes, but there are tradeoffs. A heavily scanned document at target 1MB will show visible compression artifacts. Set the target as high as your use case allows for better legibility.

The real difference

Why KuroPDF exists

Every other PDF tool uploads your files to their servers. We think that is broken. Here is what we do differently - and what the alternatives actually cost you.

Nothing leaves your device

Files are processed in your browser using WebAssembly. Open DevTools → Network tab and verify: zero upload requests. Ever.

What competitors do instead:

Smallpdf, iLovePDF, and Adobe Acrobat all upload your files to their servers - your contracts, bank statements, and medical records pass through third-party infrastructure.

No file size limits, no daily caps

Process a 500-page PDF or batch-convert 200 photos. No cap, no throttle, no upgrade wall. Your device is the only limit.

What competitors do instead:

Smallpdf limits free users to 2 tasks per day. iLovePDF caps file sizes at 100MB. Adobe requires a $19.99/mo subscription for basic features.

Works completely offline

Install KuroPDF as a progressive web app. After the first visit, every tool works with zero internet - on a plane, in a bunker, wherever.

What competitors do instead:

Every cloud-based PDF tool stops working the moment your Wi-Fi drops. No connection = no work.

Real encryption, not security theatre

Password protection uses AES-256 encryption via a WebAssembly build of qpdf. The password never leaves your machine - there is no server to intercept it.

What competitors do instead:

When you 'protect' a PDF on Smallpdf or iLovePDF, your unencrypted file and password travel to their server, get processed, then get sent back. That is not security.

Free forever, no account needed

No login wall, no email harvesting, no 'continue with Google' popup. Open the site, use the tool, close the tab. Done.

What competitors do instead:

Adobe charges $239/yr. Smallpdf charges $108/yr. iLovePDF charges $84/yr. All require account creation to use basic tools.

Professional-grade codecs

MozJPEG for JPEG, OxiPNG for PNG, AVIF and WebP encoders - the same codecs used by Google and Mozilla. Not generic re-encoding.

What competitors do instead:

Most cloud tools use basic server-side encoders with less optimization control. You get worse compression at lower quality.

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