Compress PDF
Shrink a PDF for email or upload. Runs in your browser.
100% in your browser No upload required Free, no signup
Tip: this first release uses lossless compression. Image-heavy scans will shrink more once we ship the "rasterize" option in the next update.
How it works
- 1Drop your PDF into the box above — no upload required.
- 2Pick a compression level. Lower quality means a smaller file.
- 3Download the compressed PDF. The original stays untouched.
Why CalmPDF
- Private by design. Your PDF is processed inside your browser. It is never uploaded to a server.
- Fast. No round trip to the cloud, so it works as fast as your laptop can run JavaScript.
- Free. All tools are free to use with no signup and no daily limits.
Frequently asked questions
Is my PDF uploaded to a server?+
No. CalmPDF processes your file entirely inside your web browser using JavaScript. Your PDF never leaves your device.
How much can CalmPDF compress a PDF?+
Typical scans and image-heavy PDFs shrink by 40–80%. Text-only PDFs are already small and compress less.
Is there a file-size limit?+
The limit depends on your browser and device memory. Most laptops comfortably handle PDFs up to 200 MB.
Does compression reduce quality?+
Images inside the PDF are re-encoded at a lower resolution. Text stays crisp. Choose the 'High quality' preset if you need to keep images sharp.
Is CalmPDF free?+
Yes. All core PDF tools are free and unlimited, supported by unobtrusive ads.