VoltType — Verify it yourself: in Offline mode, your audio is transcribed on your own PC and not sent anywhere

For your IT department. Takes 10 minutes. Uses the operating system's own evidence, not our word.

What you are checking

In Offline mode, VoltType transcribes on your own PC. This procedure shows two things:

While you dictate offline, VoltType sends no audio and no text. Other background requests are blocked, with two exceptions that can still go out in Offline mode: the subscription check (at most every 6 hours), and, if “Automatic updates” is on in Settings > Data, a once-a-day check for a newer version (in Offline it only announces it; nothing is downloaded). Something you press yourself, such as “Refresh plan”, signing in or “Check once” for updates, also goes out when you press it. Switch off the licence and plan check and automatic updates in Settings > Data, press nothing of the kind, and the VoltType process opens no network connection at all during Phase A.
After you switch back to Online, Online, the app talks to VoltType's API and sign-in service, and downloads offline models from Hugging Face, GitHub and our own storage when you choose them. The dictation request carries the new audio — nothing you dictated offline. (What was dictated or learned in Offline mode is kept out of every cloud request by design; the automated test tests/unit/offline-mode-fence.test.js in our repository asserts it.)

What you need

Windows 10/11 PC with VoltType installed (Microsoft Store or installer).
Wireshark (free, wireshark.org) — installs tshark, the command-line capture.
A PowerShell window run as Administrator.
The script prove-offline.ps1 (in the VoltType repository under tests/egress/, or from us on request).

Procedure

Close VoltType completely (tray icon → Quit).
In VoltType's Settings, note your toggle hotkey (default Ctrl+Shift+D).
Run, as Administrator, from the folder that holds the script:
```
powershell -ExecutionPolicy Bypass -File prove-offline.ps1 -Exe "C:\Users\<you>\AppData\Local\Programs\volttype\VoltType.exe" -Hotkey "^+d" -Secs 60
```
(^+d is Ctrl+Shift+D in the script's key notation; Wi-Fi is assumed — add -Interface "Ethernet" if you are on cable.)

The script starts the capture and VoltType, then says "switch to OFFLINE now" — do it in the app within 30 s (Offline turns off cloud dictation and usage counts by itself; for this test, also switch off the licence and plan check and automatic updates in Settings > Data).
Phase A: Notepad opens, the hotkey is pressed for you — speak for 60 seconds. The hotkey is pressed again; your text appears in Notepad.
Phase B: the script pauses 15 s — switch VoltType to Online in the app. Speak again for 60 seconds.
Read the result block.

What a correct result looks like

PHASE A  Offline
  connections opened by VoltType : NONE
PHASE B  Online
  connections opened by VoltType : <ip>:443 Established        (api.volttype.com)

The capture file (%TEMP%\volttype-egress\capture.pcapng) is yours: open it in Wireshark, filter tls.handshake.extensions_server_name contains "volttype", and confirm that the first VoltType packet appears only in Phase B.

Why the "later" objection is covered

A cloud product could transcribe offline and upload the text once the network is back. Phase B is in the procedure for exactly that reason: the first Online request is the new dictation's audio plus a short learned-terms list (a few hundred bytes); its size and timing are visible in the capture. A 60-second offline dictation is roughly 100 KB of compressed audio — if it were being uploaded later, you would see it.

What this does not prove

That our cloud service keeps no data. For that see our privacy policy (sub-processors listed) and the account export at /v1/account/export.
That the binary contains no hidden path we did not run. A third-party penetration test can be arranged as part of a pilot contract; the procedure above is what such a test would automate first.

Our own results (2026-09-18, VoltType 1.2.120 installed build, Windows 11, Wi-Fi, Windows Filtering Platform audit log)

Run by the founder on his own PC with this exact script, 60-second dictations, speaking normally:

PHASE A  Offline  01:13:44-01:14:54
  connections opened by VoltType.exe (Windows audit log): NONE
PHASE B  Online   01:15:14-01:16:22
  connections opened by VoltType.exe (Windows audit log): 172.67.209.27:443 UDP 01:16:14   (volttype-api.crcaway.workers.dev)

History that matters: version 1.2.119 showed two small sockets from VoltType.exe three seconds after an offline dictation (the browser engine inside the app pre-warming connections underneath the request gate). 1.2.120 closes that by giving the engine a dead proxy while Offline. We publish this because a customer's IT will find it anyway - and because the fix is exactly what the procedure above is for.

The script ships inside the app as prove-offline.ps1, or email [email protected].

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