What happens to a file after you close the tab
Browser tools never upload it. Server tools keep it for about an hour, then delete it.
There are two paths, and the tool page says which one you are on.
In the browser, the PDF is read by the page you already downloaded. Merge, split, rotate, watermark, organize, and the local image tools work this way. Closing the tab drops the file. FileNest stored a usage line, not the document.
On the server, compression, passwords, Word conversion, and the higher-resolution image export need programs that live next to the app. The result is saved under a random name so you can download it again from history. About an hour later the janitor removes it. The history row can remain, with the original file name and the size, and the download link dies.
An optional account stores your email, your name, and a password hash. It is how Free limits rise from the guest cap, and how Pro history and API keys attach to a person. You can use the basic tools without creating one.
Nothing on this list is an advertising profile. FileNest does not run third-party ads, and it does not sell the contents of a file it was only supposed to hold for an hour.