PDF Under is a free browser-based PDF toolkit. You can compress, merge, split, convert to images, convert images to PDF, and rotate pages — all without uploading anything. No installs, no sign-ups. Just open the page and go.
Yes, completely. Everything runs locally in your browser. Your files never leave your computer — nothing is uploaded to any server. Close the tab and everything's gone.
It depends on the target size you set. A bigger target means a clearer result, while a smaller target may lose some sharpness. The tool automatically finds the best balance between size and quality for you.
Yes, dozens of pages are no problem at all. Very large files may take a bit longer since everything runs in your browser, but it handles them just fine.
Totally free. No account needed, no hidden fees, no watermarks. Use it as many times as you want.
No, compression converts each page into an image, so text can no longer be selected or copied. If you need the text, copy it before compressing.
Bookmarks from individual files aren't carried over. The merged PDF contains all pages in order but starts fresh without the original bookmarks.
Not at all. Splitting creates a brand-new PDF with just the pages you picked. Your original file stays completely untouched.
When using the PDF to images tool, 72 DPI is good for quick screen viewing, 150 DPI works well for general use, and 300 DPI is ideal for printing. Higher DPI means bigger files, so pick what fits your needs.
The image to PDF tool supports JPEG and PNG. You can mix both formats in a single PDF — just add the images and the tool handles the rest.
Not at all. Rotation simply changes a page property — no re-rendering happens, so quality stays identical to the original.
There's no hard limit. But since everything runs in your browser, very large files (100+ MB) might be slow or use a lot of memory. For most everyday PDFs, you won't run into any issues.
Last updated: March 8, 2026