Sono

Dictation for macOS that runs entirely on your Mac. Hold a key, speak, and the text appears in whatever app you're using. No audio or transcript ever leaves the device.

Free, MIT licensed, and there is nothing to buy: no account, no licence key, no trial.

Download for macOS — signed and notarised, macOS 26+.

How it works

mic → AVAudioEngine (16 kHz mono)
    → Parakeet TDT 0.6B v3 int8, via sherpa-onnx / ONNX Runtime
    → Apple Intelligence (Foundation Models): self-corrections, grammar, lists
      — optional, and off by default: the first run should be as fast as the Mac allows
    → regex sweep for fillers the model missed
    → clipboard + synthetic ⌘V into the focused field
    → appended to history.jsonl

Two deliberate properties:

• Your speech is never networked. Sono makes exactly two kinds of HTTP request, and neither carries audio or text: the one-time model download on first launch, and Sparkle's daily check for a new version, which sends only a version number and can be turned off in Settings.
• The language model is never trusted. Polisher rejects its output if it is empty, doubles in length (it answered instead of editing), halves in length (it ate a clause), or opens with a refusal. Any rejection pastes the raw transcript instead, so a bad model day costs polish, never words.

Building

Requires Xcode 26+ and macOS 26+.

Scripts/fetch-sherpa.sh    # 103 MB of sherpa-onnx libs, not in git
xcodegen generate          # .xcodeproj is generated from project.yml
xcodebuild -project Sono.xcodeproj -scheme Sono -configuration Debug build

Then launch the built .app directly:

open ~/Library/Developer/Xcode/DerivedData/Sono-*/Build/Products/Debug/Sono.app

Do not use Xcode's ▶ Run button. Sono's UI is a floating NSPanel; when the debugger pauses the process the island freezes, permission dialogs are orphaned, and the process resists SIGKILL until its debugserver parent is killed.

Layout

File	Role
SonoApp.swift	app entry, and the record → transcribe → polish → paste loop
Island.swift	the floating pill (non-activating panel) and the brand mark
Recorder.swift	mic capture, resampled to 16 kHz mono
ParakeetTranscriber.swift	sherpa-onnx recognizer, chunked at silent points
Polisher.swift	Apple Intelligence cleanup, with output guards
Cleanup.swift	regex fillers and stutters; preserves list formatting
Injector.swift	clipboard + synthetic ⌘V, clipboard restored after
ModelDownloader.swift	first-run model fetch, checksum-verified
DashboardView.swift	dashboard, history and settings; palette and theming
Metrics.swift	all dashboard figures, derived from history
Hotkey.swift	⌥ tap to toggle, ⌥ hold for push-to-talk

Things that cost a day to learn

• Hardened Runtime silently denies the microphone with no dialog unless com.apple.security.device.audio-input is in the entitlements.
• A bare F9 never reaches an app when "Use F1, F2… as standard function keys" is off, because macOS delivers it as a media key. Hence the ⌥ modifier trigger.
• A SwiftUI .shadow() on the island gets clipped by the panel bounds when the pill grows, drawing a hard rectangle. Depth comes from the window shadow only.
• Cleanup must only touch horizontal whitespace, or it flattens the lists the polish layer produces.

Licence

Sono is MIT licensed; see LICENSE.

It stands on work by others, all of it attribution-only and none of it copyleft:

• NVIDIA Parakeet TDT 0.6B v3, CC BY 4.0. Quantised to int8 here and mirrored at aeyar-studio/sono-models.
• sherpa-onnx, Apache 2.0, with ONNX Runtime under MIT.
• Sparkle, MIT.
• Plus Jakarta Sans and Fraunces, SIL OFL 1.1.

Full attributions, including the statement of modification the model's licence requires, are in NOTICE.md.