Why you should verify, not just trust

Privacy claims are cheap. "We delete your file after 24 hours", "We use military-grade encryption", "We never share your data" — all of these are meaningless if your file was uploaded in the first place. The only way to know for certain is to watch what your browser actually sends.

Every modern browser has a built-in tool that shows you exactly what network requests a page makes, including what data is sent. You do not need any extra software.

Step-by-step: Chrome and Edge

Open the PDF converter you want to test.
Press F12 (Windows/Linux) or Cmd+Option+I (Mac). DevTools opens.
Click the Network tab at the top of the DevTools panel.
Click the ⊘ Clear button (a circle with a diagonal line) to clear any existing entries from the log.
Make sure recording is active — the round record button in the top-left of the Network panel should be red.
Drop your PDF file onto the converter and start the conversion.
Watch the Network tab while the conversion runs. You are looking for any entry where the domain is not the converter's own domain.

Red flag: If you see a POST or PUT request to any external domain with a large payload (matching your file size), your file was uploaded. If the Network tab stays empty or shows only requests to the converter's own domain, the conversion is local.

What to look for

In the Network tab, each row is one network request. The columns you care about:

Name — the URL of the request. If it goes to a domain you do not recognise (amazonaws.com, cloudflare.com, api.something.com), it is external.
Method — POST or PUT with a large payload usually indicates a file upload. GET requests are usually just loading assets.
Size — compare to your file size. A request payload similar in size to your PDF strongly suggests the file was sent.

Step-by-step: Firefox

Press F12 or Cmd+Option+I.
Click the Network tab.
Click the trash icon to clear existing requests.
Drop and convert your file.
Inspect the entries as described above.

Step-by-step: Safari

Enable the Develop menu: Safari → Settings → Advanced → Show Develop menu.
Press Cmd+Option+I to open Web Inspector.
Click the Network tab.
Clear existing entries and run the conversion.

Testing PrivaPDF

When you test PrivaPDF with the steps above, here is what you will see:

On the very first visit, two requests to privapdf.net: the Web Worker script (converter.worker.js) and the WebAssembly binary (pdf.worker.wasm). These are the conversion engine being downloaded and cached locally.
On every subsequent visit, zero network requests during conversion — everything is served from the local Service Worker cache.
Your file data: never transmitted, not even in an encrypted payload.

You can also enable Airplane Mode after your first visit and convert again. It will work identically — because nothing needs the internet.

Testing other converters

Use the same steps on any converter you want to evaluate. A few observations from our testing (as of 2025):

Smallpdf — file is uploaded to AWS S3 within seconds of dropping it. Visible in Network tab as a PUT request to an amazonaws.com URL.
Adobe Acrobat Online — file is transmitted to Adobe's servers before any processing occurs.
ILovePDF — upload to ilovepdf.com servers, confirmed in Network tab.

None of this makes those tools bad products. But it does mean "privacy" claims need to be evaluated against what the Network tab actually shows — not what the marketing says.