Compress PDF – Reduce File Size

Real compression powered by Ghostscript — shrinks images inside your PDF, not just metadata. Choose your quality level and download a smaller file in seconds.

Drop your PDF here

or click to browse — max 150 MB

Runs entirely in your browser No file upload to any server No sign-up required

How to compress a PDF online

PDF files grow large quickly — especially when they contain high-resolution images, scanned pages, or embedded fonts. A large PDF can be hard to email, upload to a portal, or share. This tool uses Ghostscript, the same PDF engine used by professional desktop software, to genuinely re-compress the images inside your PDF.

Step-by-step instructions

  1. Upload your PDF. Click the upload area or drag your file onto it. Files stay in your browser — nothing is sent to a server.
  2. Choose a quality level. Balanced (150 dpi) suits most documents. High quality keeps more detail for printing. Maximum compression gives the smallest file.
  3. Click Compress PDF. Ghostscript loads once (~18 MB, takes 10–30 seconds on first use) then processes your file. You will see the before and after file sizes.
  4. Download and verify. Open the result before sending it to anyone. Keep the original as a backup.

Why is this different from other browser tools?

Most browser-based PDF compressors only strip metadata — they cannot touch the images inside the file, which is where most of the size lives. This tool uses Ghostscript compiled to WebAssembly, which means it runs the real Ghostscript PDF engine inside your browser. It can actually re-sample and re-compress embedded images, just like the desktop application would.

The trade-off is that Ghostscript WASM is about 18 MB, so the first load takes longer than a simple tool. After the first compression the engine stays loaded, so further compressions in the same session are much faster.

What do the quality levels mean?

  • High quality (printer, 300 dpi): Images are kept at 300 dots per inch. Best if you need to print the result. Compression is modest — typically 10–30%.
  • Balanced (ebook, 150 dpi): The recommended setting for most people. Images are resampled to 150 dpi, which looks good on screen and prints acceptably. Typically achieves 40–70% reduction.
  • Maximum compression (screen, 72 dpi): Images are reduced to 72 dpi — screen resolution. Text and vectors remain sharp but photos will look soft. Best when file size is the only priority. Can achieve 70–90% reduction on image-heavy PDFs.

Privacy

Your file never leaves your device. Ghostscript runs entirely in your browser tab via WebAssembly. No file is uploaded, no account is required, and nothing is logged. This makes it safe for confidential documents including bank statements, contracts, and medical records.

Frequently asked questions

Common questions about compressing PDFs with Ghostscript.

Why does the first compression take so long?

Ghostscript WASM is about 18 MB — your browser needs to download it once. After that it stays cached, so future compressions in the same browser session start immediately. This is the trade-off for having real image compression run privately in your browser.

Why is my file barely smaller?

If your PDF contains mostly text and vector graphics (not photos or scans), there is little image data to recompress. Text and vectors are stored efficiently already. PDFs made from scanned documents or with many photographs will compress much more significantly.

Will compression affect the text quality?

No. Ghostscript keeps text and vector graphics as vectors — they are not affected by the dpi setting. Only raster images (photographs, scan backgrounds) are resampled. Your text will remain perfectly sharp at any zoom level.

Can I compress a password-protected PDF?

No. Password-protected PDFs cannot be processed. Remove the password protection first using appropriate software, then compress the file.

Is my file sent to a server?

No. Ghostscript runs as WebAssembly inside your browser tab. Your file never leaves your device. This is verifiable by opening your browser's network tab — you will see no file upload requests.