Free PDF Compress Tool — Shrink File Size in Your Browser

Large PDF files are a routine headache — an email attachment that bounces because it exceeds a size limit, a scanned document that takes forever to upload to a government portal, or a design proof that's too heavy to share over a slow connection. This tool reduces a PDF's file size directly in your browser, with two different approaches depending on what kind of PDF you're working with and what trade-off you're willing to make.

Honest Trade-Off: The Two Modes Explained

It's worth being upfront about how PDF compression actually works, because not every "free PDF compressor" online is honest about this. A PDF's size is usually dominated by embedded images (scans, photos, high-resolution graphics), not by its text — text itself takes up very little space. That means there are really two different things a compressor can do:

Optimize Structure Only re-saves the PDF's internal structure more efficiently — removing redundant data and reorganizing how objects are stored — without touching any images or text. This keeps every page fully intact, with selectable and searchable text, but typically only saves a modest amount, often just a few percent. It's the right choice for text-heavy documents like contracts, reports, or forms where preserving selectable text matters more than shaving off file size.

Compress Images (Rasterize) takes a fundamentally different approach: it renders every page of your PDF as an image at a resolution you choose, then re-saves that image as a compressed JPEG, and rebuilds a new PDF from those images. This can shrink a large, image-heavy or scanned PDF dramatically — often by 70-90% — because JPEG compression is far more efficient than a raw embedded image or scan. The trade-off is that every page becomes a picture: any text that was previously selectable, searchable, or copyable will no longer be, since the whole page is now a flat image. For scanned documents that were already just images to begin with, this trade-off costs nothing, since there was no selectable text to lose in the first place.

How to Choose the Right Mode

If your PDF is a scanned document, a photo-heavy brochure, or a design file, use "Compress Images" — you'll get the biggest size reduction and you likely weren't relying on selectable text anyway. If your PDF is a text-based document like a Word-exported report, invoice, or contract where you or the recipient need to copy text or use Ctrl+F to search, use "Optimize Structure Only" to avoid losing that functionality, even though the size reduction will be smaller.

Step-by-Step Usage

Upload your PDF and the tool will show its current file size. Choose a compression mode; if you pick "Compress Images," also choose an image quality level and a resolution (scale) — Medium settings on both give a good balance between file size and visual sharpness for most documents, while Low settings maximize savings for cases where the smallest possible file matters more than crisp detail. Click "Compress PDF" and, once processing finishes, download your result and compare the new file size against the original.

Privacy and Cost

Every step — rendering, compressing, and rebuilding the PDF — happens locally in your browser using JavaScript libraries; your file is never uploaded anywhere. There's no sign-up, no watermark, and no daily limit on how many times you can use this tool.

Frequently Asked Questions

Why did my file size barely change with "Optimize Structure Only"?

That mode only reorganizes the PDF's internal structure without touching embedded images, which are usually what make a PDF large in the first place. If most of your file's size comes from images or scans, switch to "Compress Images" for a much bigger reduction, keeping in mind that it will make text unselectable.

Will "Compress Images" make my text blurry?

At Medium or High resolution settings, text usually stays sharp enough to read comfortably on screen and in most prints, but because the whole page becomes an image, zooming in very far will eventually show pixelation, unlike true vector text. If crisp text at any zoom level matters, use "Optimize Structure Only" instead, or choose the High resolution setting in rasterize mode.

Can I get my text back to be selectable after using Compress Images?

No — once a page has been flattened to an image, the original selectable text is gone from that file. Keep a copy of your original PDF if you might need selectable or searchable text again later.

Is there a file size this tool can't handle?

There's no hard limit built into the tool, but very large or very high-page-count PDFs will take longer to process since everything runs on your device's own processing power. If a large file feels slow, try Low resolution and quality settings, or split the PDF into smaller sections first using the PDF Split tool.