Does compressing remove selectable text?
Not by default. The Recommended mode works like Acrobat's Reduce File Size: it downsamples and recompresses the images embedded in your PDF while preserving text, fonts, vector graphics, links, and form fields. Only the optional Maximum mode re-renders pages as images — use it for scans or when you need the absolute smallest file and don't need selectable text.
How does the Recommended mode work?
It analyzes how large each embedded image actually appears on the page, downsamples any image stored at a higher resolution than the chosen target, re-encodes it as an optimized JPEG, and then rebuilds the PDF's internal streams. Images it can't process safely are left untouched, and the result is never larger than the original. The result card shows how many images were recompressed.
Which level should I choose?
The presets apply to both the Recommended and Maximum modes. Screen gives the smallest files for on-screen viewing, eBook is a good balance for reading, Print stays sharp for desktop printing, and Prepress keeps the highest quality. Use custom settings for fine control over resolution and quality.
How much smaller will my PDF get?
It depends heavily on the original. Image-heavy or inefficiently-saved PDFs can shrink dramatically; already-optimized or text-only PDFs may not shrink much — the tool shows the exact before/after size so you can decide.
Are my files uploaded?
No. Compression runs entirely in your browser using pdf.js, pdf-lib, and qpdf compiled to WebAssembly, so your document never leaves your device.
What does the Lossless mode do?
It compresses by regenerating and re-deflating the PDF's internal streams and linearizing the file, without touching any image. Quality is pixel-for-pixel identical and everything is preserved; the savings are the most modest of the three modes.
