FastWord

Local, private, push-to-talk dictation for macOS — powered by whisper.cpp running entirely on-device.

Hold a hotkey, speak, release — your words appear in any focused text field. Nothing leaves your Mac.

Why

Wispr Flow / Superwhisper / Aiko are great, but they ship audio off your machine, charge a subscription, or both. FastWord is:

• 100% local. Audio never leaves your Mac. No cloud, no telemetry, no account.
• Tiny. ~520 MB DMG (Whisper turbo Q5 model included). No background download on first launch.
• Fast. Native Swift app + native Rust sidecar around whisper.cpp with Metal acceleration on Apple Silicon. Sub-second end-to-end.
• Light when idle. The sidecar evicts the model from RAM after configurable idle time (default 10 min). Your MacBook keeps its memory.
• Hackable. Sidecar architecture means you can swap in a different ggml model without touching the Swift app.
• Open source, MIT.

RAM footprint vs Wispr Flow

Measured on the same MacBook (Apple Silicon, macOS 26), both apps installed:

State	Wispr Flow	FastWord (v0.2)
Idle (not dictating)	~800 MB	~125 MB
Active (transcribing)	~1 GB	~750 MB
After idle eviction	~800 MB	~125 MB again
Architecture	Electron + cloud transcription	Native Swift + Rust + whisper.cpp
Pricing	$144/year	Free, MIT

Wispr Flow keeps ~800 MB resident even when you're not dictating because Electron + background JavaScript processes never sleep. FastWord drops the model from RAM after the configured idle window, so you only pay the memory cost while you're actually using it. (Wispr Flow idle RAM is widely reported on Reddit and review sites.)

Requirements

• macOS 13 (Ventura) or later. Apple Silicon (M-series).
• For development from source:
  • Homebrew
  • Xcode Command Line Tools (xcode-select --install)
  • xcodegen (brew install xcodegen)
  • Rust toolchain with the aarch64-apple-darwin target

Install

From DMG (recommended)

Download the latest signed and notarized .dmg from Releases, drag FastWord.app to Applications, and launch. The Whisper turbo Q5 model is bundled inside the app — no first-run download.

From source

git clone https://github.com/VasenevEA/FastWord.git
cd FastWord
brew install xcodegen rust

# One-time signing setup — copy the example and fill in your Team ID.
cp LocalConfig.xcconfig.example LocalConfig.xcconfig
# Edit LocalConfig.xcconfig and set DEVELOPMENT_TEAM = YOUR_TEAM_ID

# Build the Rust sidecar (downloads & compiles whisper.cpp on first run).
( cd sidecar-rust && cargo build --release )

# Generate Xcode project and build the app.
./scripts/build.sh
open build/Build/Products/Debug/FastWord.app

The first launch will download the Whisper Q5 model (~550 MB) into ~/Library/Caches/fastword/models/ if it's not already present.

Permissions

On first launch macOS will ask for:

1. Microphone — to record your voice.
2. Input Monitoring — so the global hotkey works system-wide.
3. Accessibility — so the transcribed text can be inserted into the focused field.

If a prompt doesn't appear, add the app manually in System Settings → Privacy & Security:

• Privacy & Security → Input Monitoring → + → select FastWord.app
• Privacy & Security → Accessibility → + → same app

After granting, fully quit and relaunch — TCC permissions only apply on a fresh process start.

Usage

• Dictate. Hold the chosen modifier key (default: Right Option ⌥), speak, release. Text is inserted at the cursor and saved to history.
• Cancel. Press Escape during recording or transcription to abort and discard the result.
• Settings. Menu-bar icon → Settings… (⌘,) — pick your hotkey, transcription language, idle eviction time, and live preview toggle.
• History. Menu-bar icon → Show History. Searchable, click rows to copy or delete.
• Quit. Menu-bar icon → Quit.

Configuration

Most things are in Settings, but the sidecar still honours these env vars:

Variable	Default	Notes
FASTWORD_MODEL	(bundled)	Path to a ggml-*.bin whisper.cpp model.
FASTWORD_IDLE_EVICT	600	Seconds of inactivity before the model is dropped from RAM.

Architecture

┌──────────────────────┐         stdio JSON         ┌────────────────────────┐
│  FastWord.app        │ ────────────────────────►  │  fastword-sidecar      │
│  (SwiftUI, AppKit)   │                            │  (Rust + whisper.cpp)  │
│                      │ ◄────────────────────────  │                        │
│  - menu bar          │                            │  - lazy-loads model    │
│  - global hotkey     │                            │  - Metal acceleration  │
│  - audio capture     │                            │  - evicts on idle      │
│  - HUD + history     │                            │                        │
│  - paste injection   │                            │                        │
└──────────────────────┘                            └────────────────────────┘

• Swift app captures 16 kHz mono Float32 PCM via AVAudioEngine, base64-encodes it, and sends a JSON request to the sidecar's stdin.
• Rust sidecar is a single ~1.5 MB binary that wraps whisper.cpp (with the Metal backend) via the whisper-rs crate. It keeps the model in RAM between requests and evicts on idle.
• Insertion path prefers Accessibility (kAXSelectedTextAttribute) so your clipboard isn't touched. Falls back to clipboard + Cmd+V (with full clipboard snapshot/restore) for inputs that don't expose AX.
• History lives in SQLite at ~/.fastword/history.sqlite.

Where things live

Path	What
FastWord/Sources/	Swift sources
sidecar-rust/	Rust sidecar (whisper.cpp wrapper)
scripts/build.sh	Generates Xcode project, builds the app
scripts/release.sh	Builds the Rust sidecar, bundles the model, signs, notarizes, packages a DMG
project.yml	xcodegen project definition (source of truth)
~/Library/Caches/fastword/models/	Cached ggml model files (used as fallback if no bundled model)
~/.fastword/history.sqlite	Transcription history

Troubleshooting

Hotkey doesn't trigger anything. Toggle Input Monitoring permission off and back on for FastWord, or run tccutil reset ListenEvent com.mrv.fastword && tccutil reset Accessibility com.mrv.fastword, then relaunch.

Build fails with xcodegen: command not found. brew install xcodegen.

cargo not found when running release.sh. Install Rust via rustup.rs.

Old ~/.fastword/venv/ from v0.1.x. v0.2.0+ deletes it automatically on first launch. The Python+MLX sidecar is gone.

Languages

The interface is localized into:

• English
• Русский
• 简体中文

Switch in Settings → Language.

The transcription engine itself supports ~99 languages — pick a specific one in Settings → Transcription language or leave on "Auto-detect".

Release & distribution

To build a notarized DMG for distribution:

1. Have a "Developer ID Application" certificate in your login keychain.
2. Store notarization credentials once:

   xcrun notarytool store-credentials FASTWORD_NOTARY \
       --key .secrets/AuthKey_XXXXXXXXXX.p8 \
       --key-id  "XXXXXXXXXX" \
       --issuer  "<issuer-uuid>"

3. Run:

   ./scripts/release.sh

   The signed, notarized DMG lands at build/release/FastWord-<version>.dmg (~520 MB with the bundled Q5 model).

License

MIT.