A context-aware browser with native voice intelligence, built on Firefox.
Website • Features • Building • Architecture
Lulu Browser is a fork of Firefox that integrates Whissle's voice intelligence directly into the browser. Instead of bolting AI onto a browser as an extension or overlay, Lulu makes ambient voice understanding, personality profiling, and intelligent assistance first-class citizens of the browsing experience.
Built on the Gecko engine, Lulu retains full Firefox compatibility — extensions, DevTools, privacy features — while adding native capabilities that a web app or extension cannot achieve.
Ambient Voice Intelligence Always-on speech recognition powered by Whissle ASR. The browser listens (with your permission), understands what you say, and acts on it — no wake word, no button press. Emotion, intent, age, and gender are detected in real-time from your voice.
Personality Meter A live indicator in the toolbar showing your current emotional state and engagement level, derived from voice analysis. It builds a behavioral profile over time, helping Lulu adapt to how you communicate.
Lulu Smartbar
The address bar doubles as a command interface. Type @lulu or speak naturally to search, navigate, summarize pages, or ask questions. Lulu understands context from the page you're viewing.
AI Sidebar A built-in chat panel with conversation memory, page awareness, and browsing history search. Powered by the Whissle gateway — your conversations are contextual and persistent.
Page Context Awareness Lulu can read and understand the content of any page you're viewing. Ask "summarize this article" or "what does this page say about pricing?" and get answers grounded in the actual page content.
Lulu Browser (Gecko Engine)
├── browser/components/lulu/ # Core Lulu services
│ ├── LuluService.sys.mjs # Lifecycle + singleton manager
│ ├── LuluAmbientVoice.sys.mjs # WebSocket STT via Whissle ASR
│ ├── LuluBehavioralProfile.sys.mjs # EMA-smoothed emotion/intent profiles
│ ├── LuluGatewayClient.sys.mjs # HTTP client for Whissle gateway
│ └── LuluDeviceAuth.sys.mjs # Device identity + auth tokens
├── browser/components/aiwindow/ # AI sidebar (chat, memories, tools)
├── browser/components/genai/ # Page assist + link previews
└── browser/components/urlbar/ # Smartbar with Lulu command mode
All Lulu services connect to api.whissle.ai — the Whissle gateway handles ASR, agent orchestration, memory, and LLM inference.
- Python 3.11+
- Rust (latest stable)
- Platform-specific dependencies (see Firefox Build Prerequisites)
# Bootstrap build environment (first time only)
./mach bootstrap
# Build
./mach build
# Run
./mach run./mach bootstrap
./mach build
./mach run./mach packageThis produces a distributable binary in obj-*/dist/:
- macOS:
.dmg - Windows:
.exeinstaller - Linux:
.tar.bz2
# Format modified files
./mach format
# Run tests
./mach test --auto
# Build only frontend changes (skip C++/Rust)
./mach build faster
# Build only C++/Rust changes (skip frontend)
./mach build binariesLulu Browser preferences are available at about:preferences#lulu:
| Preference | Default | Description |
|---|---|---|
browser.lulu.gateway.url |
https://api.whissle.ai |
Whissle gateway endpoint |
browser.lulu.ambient.enabled |
true |
Enable ambient voice listening |
browser.lulu.personality.visible |
true |
Show personality meter in toolbar |
browser.lulu.behavioral.sync |
true |
Sync behavioral profile to gateway |
Lulu Browser is built on Mozilla Firefox. We are grateful to the Mozilla community for building and maintaining the open-source Gecko engine.
The AI and voice intelligence features are powered by Whissle.
This project is licensed under the Mozilla Public License 2.0 — see the LICENSE file. Lulu-specific components in browser/components/lulu/ are also available under MPL-2.0.