Combine PDFs into one file, or pull out the pages you need. Your documents never leave your browser; there is no server to upload them to.
In Merge, drop in two or more PDFs and put them in the order you want with the arrows, then save the combined file. In Split, drop in one PDF and either extract a range of pages into a single new document, or break every page out into its own file.
Page order in a merge is list order. Files stack in the order you added them — use the up and down arrows to rearrange before merging.
Extracting pages doesn't alter the original file. You get a new document in the tray; the PDF on your disk is untouched.
No page thumbnails in this version. The page numbers you type refer to the PDF's own order, the same numbering your PDF reader shows in its page field.
This matters most with documents — contracts, tax forms, anything private. You don't have to take our word for it: every browser has a built-in panel that shows everything a page sends or receives over the internet. On a computer (this doesn't work on a phone):