How can I be sure the PDF isn't uploaded?

Open your browser's DevTools (F12), go to the Network tab, and watch for requests while you use the tool. No outbound requests appear: all processing happens entirely in your browser tab using pdf-lib.

Why compress a PDF without uploading?

Some files are not appropriate to send to a third-party service, and some networks block uploads altogether. This tool processes the PDF locally in your browser using pdf-lib, so the file never leaves your device.

Is there a file size limit?

Each PDF can be up to 100 MB. Larger files are rejected with a clear error before any processing starts.

Which quality setting preserves the most content?

Lossless mode restructures the PDF without changing any content. Text remains selectable, images are unmodified, and bookmarks are preserved. Image-based modes (High, Medium, Low) re-render pages as JPEGs, which reduces file size more aggressively but makes text non-selectable.

Compress PDF Without Uploading

Reduce your PDF file size entirely in your browser. All processing runs in your browser, with no third-party service or external storage involved. Choose lossless optimisation to keep all content intact, or pick a lower quality level for maximum file size reduction.

Drop a PDF here or click to browse

How it works

Selecting a PDF only loads the bytes into the browser's memory through the File API. Lossless mode then asks pdf-lib to rewrite the document with object stream compression, while the image-based modes spin up pdfjs-dist to render pages to a Canvas and let pdf-lib embed the resulting JPEGs. Both pipelines complete inside this tab with no upload step.

Processing runs in your browser

Because the entire pipeline runs in your browser, there is no upload step to inspect, intercept, or breach. You can open the DevTools Network tab while compressing and watch zero outbound requests fire, the PDF stays in this page from selection to download. You can check this yourselfin your browser's DevTools Network tab.

Related operations

To stitch multiple PDFs into one before compressing, try merge PDF. For pulling out a subset of pages, use split PDF. To extract pages as standalone images, see PDF to image.

Frequently asked questions

How can I be sure the PDF isn't uploaded?: Open your browser's DevTools (F12), go to the Network tab, and watch for requests while you use the tool. No outbound requests appear: all processing happens entirely in your browser tab using pdf-lib.
Why compress a PDF without uploading?: Some files are not appropriate to send to a third-party service, and some networks block uploads altogether. This tool processes the PDF locally in your browser using pdf-lib, so the file never leaves your device.
Is there a file size limit?: Each PDF can be up to 100 MB. Larger files are rejected with a clear error before any processing starts.
Which quality setting preserves the most content?: Lossless mode restructures the PDF without changing any content. Text remains selectable, images are unmodified, and bookmarks are preserved. Image-based modes (High, Medium, Low) re-render pages as JPEGs, which reduces file size more aggressively but makes text non-selectable.

Compress PDF Without Uploading

How it works

Processing runs in your browser

Related operations

Frequently asked questions

Related tools