How local processing works

Most online PDF tools upload your file to their servers, process it there, and send the result back. HandyPDF works differently: the tools are programs that run inside your browser tab. When you choose a file, your browser reads it from your disk into memory, processes it, and saves the result straight back to your device.

What runs on your device

• pdf.js (by Mozilla, the engine behind Firefox’s PDF viewer) renders pages, creates thumbnails and extracts text.
• pdf-lib merges, splits, rotates, signs and encrypts PDF files.
• JSZip bundles multiple results into one ZIP download.

The full list, with licenses, is on our open-source licenses page.

Verify it yourself

• Network panel: open your browser’s developer tools (F12 or ⌥⌘I), switch to the Network tab, then use any tool. You’ll see the page’s own files load once — and no request carrying your document.
• Turn off Wi-Fi: once a tool page has loaded, disconnect from the internet and use it. It keeps working, because nothing needs a server.
• Content Security Policy: our pages tell the browser they may only connect to handypdftools.com itself, so even a bug couldn’t send your file to another server.

Limits of local processing

Because your device does the work, very large files depend on your computer’s or phone’s memory. Some conversions — such as PDF to Word — can’t be done well inside a browser yet. If we ever offer a tool that needs a server, it will be clearly labeled on that tool’s page before you choose a file.

So how is it free?

Running code in your browser costs us almost nothing — there are no processing servers to pay for. The site is supported by a small number of unobtrusive ads, never placed inside a tool while you work.