PDF Compressor

Reduce the file size of a PDF right in your browser — no upload, no server, no file size limit beyond your device's memory.

How to use

  1. Choose a PDF file from your device (up to 50 MB).
  2. Click "Compress PDF" — the library loads on demand and processes the file in your browser.
  3. Download the compressed file. The original and compressed sizes are shown so you can see how much was saved.

About this tool

This tool re-saves a PDF using the pdf-lib library, which runs entirely in your browser. The compression comes from stripping redundant objects, re-encoding streams and removing metadata that inflates the file — the same operations a desktop tool would perform, without installing anything. The result depends on the source: a PDF exported from a word processor with embedded fonts can shrink significantly; a PDF that is already optimized may barely change.

The file never leaves your device. The library loads on the first click (it is large enough to delay the page otherwise), reads the PDF from memory, re-saves it, and offers the result as a download. No server receives the file, no copy is stored, and the processing happens in the browser's own memory. The practical limit is your device's RAM, not a server quota.

Image-heavy PDFs may not shrink much because the images inside them are already compressed (usually JPEG). For those, the biggest gain comes from downscaling the images before embedding them, which this tool does not do — it works on the PDF structure, not on the pixel data inside it.

Frequently asked questions

Is the PDF uploaded to a server?

No. The entire process runs in your browser. The file is read into memory, processed by the pdf-lib library, and the result is offered as a local download. Nothing is transmitted.

Why did my PDF barely shrink?

Because it was already optimized or because most of its size comes from embedded images, which this tool does not re-encode. PDFs from word processors and presentation software tend to shrink more than scanned documents.

Is there a file size limit?

The practical limit is your device's RAM. The tool caps at 50 MB to keep the experience reasonable on most devices.

Does compression affect quality?

No — this is lossless structural optimization. Text, images and vector graphics remain identical. The savings come from removing redundancy in the file structure.

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