Measured in this tab
Do not take the privacy claim on faith.
This page loads a real text file, removes duplicate lines with the same local module used by FileGizmo tools, and reports what your browser observed.
Live proof run
proof-sample.txt
Checking connection
The browser is preparing the sample.
The request count uses the same origin test as the live footer counter. Same-origin page assets are not presented as off-origin traffic.
Test two
Disconnect, reload, repeat.
Open this page once while connected and wait for the proof run to finish. Then disconnect the network, reload, and press the button. The cached page, sample, and processor continue to work locally.
The first visit needs a connection. Clearing site data removes the cache, and a tool with a large engine may need its own assets loaded once before it can work offline.
The honest exception
Address geocoding contacts Geoapify.
The Address to coordinates tool cannot derive map coordinates offline. It sends each address and a user-supplied API key directly to Geoapify. That permission exists only on that route. The full CSV is not sent to FileGizmo.
Every ordinary file tool keeps the stricter same-origin connection policy described on the security page.