Compress PDF
Reduce PDF file size for email or storage while keeping pages readable. PDF Lab compresses your file directly in the browser — nothing is uploaded to any server.
or drop files here
Tip: select a single file.
How to use Compress PDF
- 1Click "Select PDF file" and choose the PDF you want to compress.
- 2Pick a compression level. Medium is a good balance of size and quality.
- 3Click Compress PDF. The optimized file is built in your browser and downloaded.
Why use PDF Lab
- Three preset compression levels plus a render scale control.
- Files stay on your device — nothing is uploaded to any server.
- No account, no signup, no watermark on the output.
- Free to use with no per-file limits beyond your device's memory.
- Works on desktop and mobile browsers, including offline after first load.
- Useful for getting PDFs under email size limits.
Your file never leaves your browser
Compress PDF runs entirely on your device using pdf-lib and pdf.js — both self-hosted by PDF Lab, so no third-party CDN sees your traffic. There is no upload, no account, no log of your file.
How browser-based PDF processing works →Compress PDF — questions
- No. Every operation runs in your browser using JavaScript. Your file is loaded into your browser's memory, processed, and a result is saved to your device. Nothing is sent over the network.
- No. Because the processing happens in your browser, neither PDF Lab nor any third party has access to the file contents. You can verify this by opening your browser's network tab while using the tools — no file data is transmitted.
- There is no enforced limit, but performance depends on your device's memory. Most modern browsers comfortably handle PDFs up to about 100 MB. Very large files may slow down your browser tab.
Are my files uploaded to your server?+
Can PDF Lab see the contents of my files?+
Are there file size limits?+
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