What is PDF compression?

PDF files balloon in size for one main reason: images. A scanned contract, a slide deck exported with high-resolution photos, or a brochure full of product shots can easily run to dozens or hundreds of megabytes — far past most email attachment limits and annoying to upload anywhere. This tool rebuilds your PDF with compressed images at the compression level you choose (low, medium, or high), trading some image fidelity for a dramatically smaller file.

How aggressive should you be? For text-heavy documents that need to stay crisp, use low — it mostly squeezes the low-hanging fruit. Medium works well for everyday sharing: reports and scans stay readable while the file often shrinks by half or more. High is for cases where delivery matters more than pixel perfection, such as getting a 50 MB scan under an email limit. After processing, the tool shows you the original and compressed sizes so you can judge whether the trade-off was worth it.

Compression is a re-encoding process: your browser loads the PDF, rewrites its image streams, and saves a new file — all locally, with no upload to any server. Confidential documents stay on your machine.

Be aware of what compression cannot do. It mainly works on image content; a PDF that is already pure text will barely shrink, because text was small to begin with. And since images are recompressed, quality loss is permanent — keep your original file, and never compress the only copy of an archival scan. For best results, compress once at the right level rather than repeatedly, which compounds the loss.