How to compress a PDF for free (without uploading it)

Email attachment too big to send? Most online PDF compressors upload your file to a server first — a problem if it holds contracts or statements. Here's how to shrink a PDF entirely on your own device: free, no signup, nothing leaves your browser.

1. Open the Compress PDF tool. Open the free Compress PDF tool on taimurtools.com. It runs locally in your browser.
2. Add your PDF. Drag in or select the PDF you want to shrink. It's read on your device — not uploaded anywhere.
3. Choose a compression level. Pick the balance you want between smaller size and visual quality. Image-heavy PDFs shrink the most.
4. Download. Click compress and save the smaller PDF. The whole process happened on your machine.

Before you start: will compression help this file?

PDFs come in two broad kinds, and compression behaves very differently on each. A scan or photo-based PDF is a stack of page pictures, usually large because each page is a full-resolution image. A text-based PDF, such as a document exported from Word or a web page saved as PDF, stores letters as text and is usually small. Compressing the first kind can make a big difference. Compressing the second kind often makes things worse.

A quick test: open the PDF and try to select a word with your cursor. If you can, it has a real text layer. If you cannot, it is a scan and is a good candidate for compression. Another clue is size per page: a single page of a typed document is usually small, while a scanned page is often hundreds of kilobytes or more.

What the tool actually does to your file

It is worth knowing the mechanism, because it explains every limitation. Compress PDF opens your file with PDF.js, draws each page onto a canvas, saves that picture as a JPEG, and builds a new PDF from the pictures with pdf-lib. All of that happens in your browser tab. Because the pages become pictures, three things follow:

• Text in the result is no longer selectable or searchable. If you need that back, run the result through OCR PDF.
• Links and form fields are gone, and a digital signature on the original no longer validates, because the file has been rebuilt.
• A PDF that was already mostly text can come out larger than it went in.

The three levels

The levels are three combinations of how large each page is drawn and how hard the JPEG is squeezed:

• Strong: pages drawn at about 72 pixels per inch, 55% JPEG quality. Smallest file; fine print can look soft.
• Balanced: about 100 pixels per inch, 72% quality. The sensible place to start for most scans.
• Light: about 144 pixels per inch, 88% quality. Larger result, best when the document has small print or stamps.

Hitting an exact size, such as 100 KB

Portals that cap uploads are the most common reason people compress a PDF. Choose the target-size option, type the limit in KB (or tap 100 KB, 200 KB, 500 KB or 1 MB), and the tool redraws the pages at lower resolution and quality, step by step, keeping the first version that fits. If none fits you get the smallest version it could make, with a plain note saying the target was not reached. In this tool 1 KB is counted as 1,000 bytes. Sites disagree about whether a KB is 1,000 or 1,024 bytes, and the smaller figure passes both.

If a long document will not reach the target, split it with Split PDF, compress the heavy part on its own and merge the pieces back together. Typed pages stay crisp and only the scanned pages are squeezed.

A sensible order of attempts

1. Try Balanced first and look at the size shown.
2. If it is still over your limit, switch to a target size and let the tool step down.
3. If the target is still not reached, split the file and compress only the heavy pages.
4. If small print has become unreadable, go back and use Light, and accept a larger file or remove pages you do not need to send.

Check the result before you send it

Open the compressed file and zoom to 100% on the smallest text. Check the page count matches the original, that stamps and signatures are still legible, and that nothing important has gone soft. Keep the original: the compressed copy is lossy and cannot be turned back into the original.

When not to use this tool

Do not use it on a document that has to stay searchable or digitally signed, or on a text-based PDF that is already small. Desktop software such as Adobe Acrobat's file-size reducer or Ghostscript can shrink the images inside a PDF while leaving the text as text, which suits those files better. Use this tool when the file is a scan, when it is sensitive and you would rather not upload it, or when you cannot install software.

FAQ

How much smaller can the PDF get?

There is no fixed percentage, because it depends on the content. A scan or photo-heavy PDF can shrink a lot; a PDF that is mostly text can actually get bigger. Try Balanced first, or type a target size and let the tool step down until it fits.

Will compressing lower the quality?

Yes. Every page is redrawn as a JPEG image, so detail is lost at every level. Strong is the smallest and softest, Light keeps the most detail. Look at the result at 100% zoom before you send it.

Is it safe for confidential documents?

The file is processed inside your browser and is not uploaded to this site or anyone else. The PDF.js and pdf-lib code that does the work is downloaded from a CDN, but your file is not sent there.

Is there a limit on how many PDFs I can compress?

Yes. Free use is capped at 5 runs per day for this tool, counted in your browser and reset at midnight UTC. TaimurTools Pro lifts the cap.

Why did my file get bigger?

It was probably a text-based PDF. Rendering text as pictures costs more space than storing it as text. Use the original, or a desktop tool that compresses only the images.

Can I get searchable text back?

Not from this tool, since the pages become images. Run the result through OCR PDF to add an invisible text layer.

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