How to compress a PDF without uploading it

SnackPDF compresses a PDF in your browser with a bundled Ghostscript WebAssembly engine. The selected file is passed to a dedicated browser Worker and an in-memory filesystem; it is not sent to SnackPDF for processing.

Compress the file locally

1. Open the private PDF compressor.
2. Wait for the site status to say “Ready for offline use” if you also want to use the tool without a connection.
3. Choose one PDF. SnackPDF shows the name and size before processing.
4. Choose Light, Balanced or Smallest. Light favours image quality; Smallest applies the strongest image downsampling.
5. Select “Compress PDF”, then download the new file. The original remains unchanged.

Check that no upload occurred

For a repeatable check, open your browser's developer tools and clear the Network panel before choosing a synthetic or non-sensitive PDF. Complete the operation and confirm that the document name, contents and password do not appear in outgoing requests. SnackPDF's own release suite performs a stricter version of this test; the exact boundary and fixtures are described on How SnackPDF is tested.

Review the result

Compression is a rewrite, not a byte-for-byte edit. Images can be resampled and comments, forms, bookmarks, links, metadata or other structures may change. A short or already compressed PDF may stay similar in size or become larger. Keep the original and inspect the saved copy at the zoom level and in the workflow that matter.

Read the privacy boundary and offline PDF tools guide for related checks.