How "nothing uploaded" works
When you open this page, your browser downloads the converter: about a third of a megabyte of WebAssembly built from libmspub, the open-source Publisher reader that LibreOffice uses. When you drop a file, the browser reads it from your disk and hands it to that converter, on your computer. The pages are drawn and the PDF is put together the same way. There's no upload step, because there's no server doing the work.
You can check this yourself. Open your browser's developer tools, go to the Network tab, and convert a file. You'll see the page's own files load, and nothing carrying your document go out. You can also load the page, switch off Wi-Fi, and convert files offline.
The page does send one tiny note to our own server when a file opens or fails to open: the type of file, whether it worked and, if not, a short reason such as "damaged". Never the file, its name or anything inside it. The privacy page has the details.
Why it matters
Publisher files often hold personal details: class lists, permission slips, rotas with phone numbers, parish directories, payroll notices. Under UK and EU data protection law (GDPR), handing those to an unknown company's server is a decision someone should be able to justify. Converting in the browser avoids the question.
How good is the PDF?
- Every page, at its real size, in one PDF.
- Text stays real text, so you can search it and copy from it.
- Photos keep their quality; old Windows clip art is redrawn sharply.
- Fonts are embedded, so the PDF looks the same on every computer.
Fonts that can't be shared are replaced by close open stand-ins, so check the pages before you rely on the PDF for something formal.
Works on locked-down computers
There's nothing to install and no administrator rights are needed, so it works on school and office laptops where you can't add programs. It also works on Chromebooks and iPads, which can't run Publisher at all.