Compress PDF
Shrink an oversized PDF right in your browser, free and with no usage limits. Colibrí re-compresses the pages to slim down scanned documents or files packed with images, perfect for emailing them or uploading them to a form with a size limit. Your file is never sent to any server: everything happens on your device, with no sign-up and no watermarks.
How to compress a PDF
- Drag your PDF onto the upload area or click to choose the file.
- Choose the compression level: maximum for the smallest size, balanced for the best trade-off, or light to keep more quality.
- Click “Compress PDF” and wait for the pages to be processed inside your browser.
- Check how much size you saved and download the compressed PDF.
Frequently asked questions
Is my PDF uploaded to any server?
No. All compression happens in your browser with JavaScript (pdf.js and pdf-lib). Your document never leaves your device, so it’s safe even with confidential files.
How does it reduce the PDF size?
Each page is redrawn as an optimized JPEG image and re-embedded into a new PDF. That’s why it works so well with scanned documents or files full of photos. The trade-off is that the text is no longer selectable (it ends up “inside” the image); if you need to keep the text, save the original as well.
Is it free? Any watermarks or limits?
It’s completely free, with no watermark, no sign-up and no daily usage limit. Unlike many websites, you don’t pay and we don’t ask for your email: you just compress your PDF and download it.
Why does the size sometimes not go down?
If your PDF is already optimized or is pure vector text (no images), converting it to images wouldn’t make it lighter and could even make it bigger. In that case the tool warns you and gives you back the original untouched, so it doesn’t make things worse.
Do I lose quality when compressing?
Yes, the compression is lossy (JPEG): the more you compress, the less sharp it looks. That’s why we offer three levels; choose “Light” if the document will be printed and “Maximum” if it will only be viewed on screen or sent by email.
Does it work with password-protected PDFs?
No. If the PDF is encrypted, the tool detects it and warns you, because it can’t read the content without the password. Remove the protection first.
Does it work offline?
Yes. Once the page has loaded, all compression happens locally, so it works without an internet connection.
Related guides
- A free alternative to password-protect a PDF without uploading it Password-protecting a confidential document by uploading it to someone else’s server is a contradiction. Here is how the known sites gate it — and a free alternative that encrypts the PDF in your browser.
- A free alternative to iLovePDF and SmallPDF for compressing PDFs The popular compressors cap free use or make you upload your file. Here is how they gate it — and a free, unlimited alternative that shrinks your PDF entirely in your browser.