Security

A security overview, for the people who have to sign it off.

Mythral is dictation and meeting notes for Mac. Speech recognition, writing and notes run on Apple silicon with local models. There are no Mythral servers, no accounts and no telemetry, so there is no customer data for us to hold, lose or hand over.

Architecture

Speech to text runs on the Mac: NVIDIA's Parakeet model on the Neural Engine for English, and whisper.cpp for 98 other languages.
Writing and meeting notes come from an open model (Qwen3.5) running on the Mac through llama.cpp.
Meetings are heard through macOS's own audio capture. No bot joins the call.
The app is signed with a Developer ID and notarized by Apple.

Every connection the app can make

An organization can turn all of these off with one setting, OfflineMode.

WhatWhereWhen

Model downloadshuggingface.coOnce, at first run, if the models were not installed. Never with the organization installer.

Update checkmythral.dev, then github.com for the downloadOnce a day. Carries the app version and nothing else. Off with UpdatesAllowed or OfflineMode.

Website wordsThe site the person types inOnly when someone adds a website for its vocabulary. Off with OfflineMode.

Microsoft 365 calendarlogin.microsoftonline.com, graph.microsoft.comOnly if someone signs in with their work account. Reads their own calendar, read-only. Nothing goes to Mythral. Off with MicrosoftCalendarAllowed or OfflineMode.

Help, feedback, email draftsmythral.dev, Gmail or Outlook on the webOpened in the person's browser when they choose. The app itself sends nothing.

What is stored, and where

WhatWhereProtection

Transcripts, dictations, notesThe app's folder in the person's LibraryEvery record encrypted with AES-GCM. FileVault covers the disk.

Meeting audioThe app's folderEncrypted with AES-GCM once the notes are written, opened only to play back. Kept only as long as the retention policy allows.

A failed dictationA temporary folderEncrypted with a key held only in memory. Deleted after five minutes.

Word listsThe app's folderPersonal lists and how each word is misheard, encrypted with AES-GCM.

Learned correctionsThe app's folderOnly the word pairs a person corrected, encrypted with AES-GCM. Listed in Settings with Remove.

Diagnostics logThe app's folderCounts and timings, never words. Leaves the Mac only if someone attaches it to a report.

ModelsThe app's folder, or shared from the installerChecked against pinned checksums before use.

Deleting a meeting deletes its transcript, notes and audio. Removing the app and its folder removes everything; there is no copy anywhere else.

Controls for organizations

Every setting can be set and locked with a configuration profile from your MDM, including offline mode, updates, meeting recording, a consent notice before each recording, and how long audio is kept. See Mythral for teams.

Permissions

Microphone, to hear the person dictating.
Accessibility, to type into the app in front, and to read a little of the screen as spelling hints for that one dictation. Password managers and banking apps are never read.
Screen & System Audio Recording, only for meetings: it is how macOS lets an app hear the other side of a call. No screen is recorded.

Requirements

Apple silicon Mac · macOS 14.4 or later. 16 GB of memory recommended for meeting notes.

Questions

For a security questionnaire, a call with your security team, or anything not covered here, talk to us. Full detail on the app's data is in the privacy policy.