Zen Browser ++

A premium, feature-rich fork of Zen Browser with built-in, end-to-end encrypted sync.

Zen Browser ++ builds on the privacy-first foundations of Mozilla Firefox and the beautiful vertical-tab paradigm of Zen Browser, adding a polished, self-hostable sync for your workspaces and tabs — encrypted on-device so the relay never sees your data.

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✨ Highlights

• 🔒 Zen Sync — end-to-end encrypted sync of spaces, tabs, groups and folders across devices, against a self-hostable relay. See limeflash/zen-sync.
• 🪟 Redesigned sync setup — an intuitive, localized (EN/RU) configuration pane with step-by-step device-pairing instructions.
• 🛟 Fail-safe account management — connect, disconnect and switch accounts instantly, with robust error handling.
• 🎨 Modern, Fluent UI — native settings cards, matching accent colors and refined spacing.
• 🛡️ Private by default — your keys, salts and passphrase never leave the device in plaintext.

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🔄 Zen Sync

The sync feature lives in its own repository — limeflash/zen-sync — and is consumed here as a git submodule at src/zen/sync:

Part	What it is
client	The in-browser module (this repo, via the submodule): crypto, relay calls, conflict-safe reconciliation, and the settings pane.
server	A self-hostable, zero-knowledge FastAPI relay — stores only ciphertext.

How it works (details in the sync repo's ARCHITECTURE and API docs):

1. A passphrase derives an AES-256-GCM key + auth token (PBKDF2, 100k iters).
2. Your state is encrypted on-device and pushed to your relay as opaque blobs.
3. Other devices pull and decrypt — the relay only ever sees ciphertext.

Run your own relay in minutes (Docker or uvicorn); see the server README. Then open Settings → Zen Sync, enter your Relay URL + passphrase, and pair devices.

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🛠️ Building

Zen Browser ++ is a full Firefox fork — building it compiles the browser engine.

Prerequisites

• Node.js v20+
• Mozilla's build toolchain — MozillaBuild on Windows; mach bootstrap on macOS/Linux.
• A Clang ≥ 19 toolchain (see configs/).

Clone (with the sync submodule)

git clone --recursive https://github.com/limeflash/zen-browser-plus
cd zen-browser-plus
# already cloned without --recursive?
git submodule update --init --recursive

Build & run

npm install
npm run build        # full engine build (the first build takes a while)
npm run package      # produce an installer/package under engine/.../dist
npm start            # run the built browser

For UI-only iteration use npm run build:ui. Release builds for Windows, macOS (incl. arm64) and Linux are produced by the workflows in .github/workflows.

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🙏 Acknowledgements

We stand on the shoulders of giants:

• Mozilla Firefox — the secure, privacy-first engine that powers the modern web.
• Zen Browser — the beautiful, innovative vertical-tab desktop browser this fork builds upon.

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📄 License

Licensed under the Mozilla Public License, v. 2.0.