Your PDF is 25 MB and the email attachment limit is 10. The form only accepts files under 5 MB. The upload keeps timing out because the file is too large. Sound familiar? These are the moments where you need to compress a PDF quickly without jumping through hoops.

This free online PDF compressor lets you reduce PDF file size directly in your browser. There is no upload to a server, no waiting for processing on someone else's hardware, and no risk of your private documents sitting on a remote machine. Everything happens locally on your device — you can even disconnect from the internet after the page loads and the tool will still work.

The tool works by re-rendering each page at a configurable quality level. You pick how aggressively you want to compress — from a light touch that barely affects visual quality to a heavy squeeze that can shrink files by 80% or more. This makes it especially effective for compressing scanned PDFs, image-heavy documents, and large presentations where most of the file size comes from embedded images.

Reducing the file size of a PDF with the PDF Compressor tool

How does it work?

The compressor reads your PDF, renders each page to a high-resolution canvas, then re-encodes it as an optimized JPEG image at your chosen quality level. These compressed page images are assembled into a brand new PDF that preserves the original page dimensions. The result is a much smaller file that looks nearly identical to the original — especially at the "Low" and "Medium" compression presets.

This is the same approach used by most popular online PDF compressors. The difference here is that we do it entirely in your browser using pdf-lib and PDF.js, so your files stay private.

How to use Online PDF Compressor?

Compressing a PDF takes about 10 seconds for a typical document:

Upload your PDF by dropping it into the upload area or clicking to browse.
Choose a compression preset — Low (best quality), Medium (balanced), or High (smallest file). You can also fine-tune the quality slider manually.
Click "Compress PDF" and watch the progress bar as each page is processed.
Once done, you will see the original and compressed file sizes side by side with the percentage reduction.
Hit "Download" to save the compressed PDF to your device.

Compression presets

Low compression — Keeps quality high, reduces file size modestly. Best when you need the document to look as close to the original as possible. Typical reduction: 20-40%.
Medium compression — Good balance between quality and file size. Fine for most everyday use cases like emailing or uploading. Typical reduction: 40-65%.
High compression — Maximum file size reduction. Some quality loss is visible on close inspection, but perfectly readable. Great for archiving or when file size limits are strict. Typical reduction: 60-85%.

Common use cases

Reduce PDF file size for email — Most email providers cap attachments at 10-25 MB. Compress your PDF to fit within the limit without splitting it into multiple files.
Compress scanned PDF documents — Scanned pages are essentially high-resolution images and tend to be huge. This tool is particularly effective at shrinking them.
Make PDF smaller for web upload — Many forms, portals, and CMS platforms impose file size limits. Shrink your PDF to meet the requirement.
Reduce PDF size for storage — Archive large collections of PDF documents without eating up disk space.
Compress PDF without losing quality — Use the Low preset to shrink PDF files with minimal visible quality loss.
Compress PDF in browser — No software to install, no server to trust. Everything runs locally.

Features

100% client-side PDF compressor — Built on pdf-lib and PDF.js. Your files never leave your browser.
Three compression presets — Low, Medium, and High with a manual quality slider for fine control.
Before/after comparison — See the original and compressed sizes side by side with percentage reduction.
Page-by-page progress — A progress bar shows which page is being processed so you know how long to wait.
No file size limits — Process any PDF regardless of size. The only limit is your device's memory.
Works offline — Once loaded, the tool works without an internet connection.
No signup required — Upload, compress, download. Nothing else.