Compress a PDF
Compress PDF shrinks a bulky file so it's easier to email or upload, showing you the before-and-after size so you can decide if the trade-off is worth it.
The re-save happens on your device, so a large private file never has to be uploaded just to make it smaller.
How to compress a PDF in three steps
- Open the PDF you want to shrink.
- Run the compression and read the before/after size.
- Download the smaller file — or keep the original if the saving is not worth it.
Why Compress PDF runs on your device
Everything happens on your device. The moment you choose a file, Compress PDF loads it directly into your browser's memory and does all the work there with WebAssembly and JavaScript — the bytes never travel to a server, because there is no server in the loop. FreePDFX enforces a strict Content-Security-Policy whose connect-src 'self' rule makes it physically impossible for this page to send your document anywhere, even by mistake. Want proof? Open your browser's Network panel and watch, or simply switch off Wi-Fi first. As an installable Progressive Web App, it keeps working fully offline once the tools are cached. FreePDFX sets no advertising or analytics cookies today, and keeps only small settings you can see and wipe any time — your PDFs are never among them, because they are never received.
Best-effort: it's a re-save, not magic
Compression is best-effort, not a lossless trick. It re-saves the file and, where the biggest savings live, re-encodes images to a lower quality — so a smaller file can mean slightly softer pictures. How much you save depends entirely on what's inside: a scan-heavy PDF can shrink a lot, while a file that's mostly text may barely move because there is little to squeeze. The before/after readout lets you judge, and you can always keep the original.
Free forever, with no sign-up and no watermarks on your results. FreePDFX exists to give you the everyday PDF tools you need without handing your documents to a stranger's server. Every tool is honest about what it can and cannot do, so you always know whether you are getting a byte-perfect result or a solid best-effort one before you download.
Frequently asked questions
Are my files uploaded anywhere?
No. Compress PDF runs entirely inside your browser. Your file is opened in local memory and processed with WebAssembly and JavaScript, and the site's Content-Security-Policy blocks every network connection except to FreePDFX's own files — so your document simply has no route off your device.
Does this work offline?
Yes. FreePDFX is an installable Progressive Web App. After your first visit the tools are cached, so you can add it to your home screen or desktop and keep using Compress PDF with the Wi-Fi off — nothing needs to download again.
Is there a file size limit?
There's no server-side limit, because nothing is uploaded. The only ceiling is your own device's memory: very large or high-resolution PDFs use more RAM, so an older phone handles less than a modern laptop. If a huge file struggles, close other tabs and try again.
Do I need to sign up or pay?
No. FreePDFX is free and needs no account, email or payment. Open a file and go — there's nothing to register, and no watermark is added to your results.
Why did my file barely get smaller?
Most of the savings come from images. A text-only PDF has little to compress, so the size may hardly change — that is expected.
Will compression blur my images?
Stronger compression re-encodes images at lower quality, so they can look slightly softer. The before/after readout helps you decide.