FreePrivateConvert

How to check a converter isn't uploading your file

By Ajiri Ogba · Updated

Open your browser's developer tools, switch to the Network tab, then convert a file. If the converter uploads it, you'll see a request (usually POST or PUT) roughly the size of your file. If it converts locally, no such request appears.

1. Open the Network tab

  • Chrome or Edge: press F12 (or Ctrl+Shift+I; on Mac, Cmd+Option+I) and choose Network
  • Firefox: press F12 (or Ctrl+Shift+E; on Mac, Cmd+Option+E)
  • Safari: turn on the Develop menu in Settings → Advanced ("Show features for web developers"), then choose Develop → Show Web Inspector → Network

2. Record a conversion

  1. Load the converter page first, then clear the list (the 🚫 / trash icon) so only new requests show.
  2. Tick "Preserve log" (Chrome/Edge) or "Persist Logs" (Firefox) so nothing disappears if the page changes.
  3. Add your file and run the conversion as normal.

3. Read what you see

Sort by size, or look at the Method column. An upload is a POST or PUT request whose request size is close to your file's size; clicking it often shows the file name under Payload or Request. Some services upload in many chunks, so add up repeated requests to the same address.

Requests that just download the converter's own code (scripts or a .wasm engine) are fine: they come towards you, not from you. Small requests of a few hundred bytes, such as page-view counts, can't carry a multi-megabyte file.

What you'll see on this site

On a video or audio tool, the first conversion downloads the ffmpeg engine (about 30MB, a GET request from this site). During the conversion itself there is no POST or PUT request, and nothing the size of your file ever leaves the browser.

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