Trezor Bridge — Secure Wallet Connection

What is Trezor Bridge?

Trezor Bridge is a lightweight, cross-platform application maintained by SatoshiLabs that facilitates communication between the Trezor hardware wallet and desktop applications or web-based wallets running in your browser. Historically, Trezor devices communicated via native browser plugins; Bridge replaced that model with a local service approach because modern browsers tightened plugin security and removed support for certain low-level USB APIs.

Why it exists

Bridge exists because browsers isolate web pages from raw hardware access for security. A local bridge process allows users to securely connect their Trezor without giving web pages direct hardware access. This makes the security model clearer: the only program with raw USB access to your device is the Trezor firmware and the Bridge process running locally on your machine — not the remote website.

How Trezor Bridge works

At a high level, Trezor Bridge runs locally and exposes a secure API on loopback (e.g., http://127.0.0.1:21325). The web wallet or Trezor Suite (the official desktop app) sends encrypted, structured requests to Bridge, which are then forwarded to the device over USB. Bridge also handles device enumeration, firmware updates (when initiated), and payload framing.

Communication flow (simplified)

• Web UI requests a connection →
• Bridge verifies and establishes the link →
• Bridge relays messages to the Trezor device →
• Device prompts the user to confirm actions →
• Signed responses return to the web UI via Bridge.

Security boundaries

The trusted UI for sensitive operations is the hardware device itself. Even if a malicious web page sends transactions through Bridge, the Trezor screen and buttons are where you verify operations. Never confirm a prompt on the device unless the displayed data matches your intention.

Installing Trezor Bridge

Installing Bridge is straightforward. There are installers for Windows, macOS, and Linux. Below are step-by-step instructions and important platform-specific notes.

Windows

1. Download the Bridge installer from the official site (link list below).
2. Run the installer as administrator and follow the prompts.
3. Once installed, the Bridge service will start automatically and will be reachable on 127.0.0.1 at the default port.
4. Open your browser and visit your wallet interface (e.g., Trezor Suite or a compatible web wallet) to connect the device.

Notes for Windows

If you use enterprise or locked-down systems, Bridge may require elevated permissions to install. For Windows 10/11, ensure you allow the driver and service during installation.

macOS

1. Download the .dmg installer from the official site.
2. Open the .dmg and drag the Bridge application to Applications.
3. Launch Bridge; macOS may require you to allow the application in Security & Privacy settings for the first run.

Notes for macOS

On macOS 10.15+ (Catalina, Big Sur, Monterey, Ventura, etc.), privacy protections may require you to approve the app in System Settings → Privacy. If you experience issues, check that Bridge has necessary permissions and that the browser you're using is up to date.

Linux

1. Choose the correct package for your distribution: .deb (Debian/Ubuntu), .rpm (Fedora), or AppImage for portable usage.
2. Install using standard package managers (dpkg, rpm) or run the AppImage directly.
3. You may need to add udev rules or give your user permission to access USB devices. The Trezor docs explain the exact udev rule to add.

Notes for Linux

udev rules are the usual source of trouble. If your device isn't detected, double-check the rules and verify your user is in the plugdev or equivalent group for your distro.

Troubleshooting common issues

The most common Bridge issues are: device not detected, browser can't connect, Bridge not running, or certificate/port conflicts. The steps below will help you diagnose and fix these problems.

Device not detected

• Try a different USB cable (use a data cable, not a charge-only cable).
• Try a different USB port (avoid USB hubs — plug directly into your machine).
• Restart Bridge or your computer and try again.

Browser can't connect

If the wallet shows a connection error, confirm Bridge is running on the local machine. On Windows, check Task Manager; on macOS, check Activity Monitor; on Linux, check ps output. If Bridge isn't running, launch it manually and refresh the wallet page.

Port conflicts and firewall

Bridge listens on a local port (default 21325). If another service uses that port, Bridge won't start correctly. Check your firewall and local security software to ensure loopback connections are allowed. Temporarily disable strict firewall rules to test connectivity.

Bridge outdated or incompatible

If you experience strange behavior, check your Bridge version and update to the latest release. Trezor regularly updates Bridge to support new firmware features and browser changes.

Security considerations and best practices

Trezor Bridge is designed to minimize attack surface and keep sensitive operations on the device. Still, you should follow best practices to keep your funds safe.

Always verify on device

The golden rule: never confirm a transaction or reveal sensitive data without checking the device screen. Bridge and web interfaces only relay messages — the device shows the final human-verifiable data.

Install Bridge from official sources

Always download Bridge from the official Trezor website or the official GitHub releases. Installing Bridge from untrusted sources could expose you to malicious software that attempts to intercept communications.

Keep software up to date

Update firmware on your Trezor device and keep Bridge and Trezor Suite up to date. Security patches and UX improvements frequently arrive in updates.

Localhost vs. remote

Bridge uses local loopback addresses, which prevents remote servers from directly connecting to the service. However, if your machine is compromised, local loopback services could be abused by malicious processes. Keep your operating system and antivirus software updated.

Advanced usage and developer notes

Developers building integrations should prefer the official Trezor Connect library, which abstracts Bridge and other transport mechanisms. If you're experimenting, here are some key points.

Programmatic access

Trezor Connect provides a high-level API for requesting signatures, enumerating accounts, and handling user confirmations. It handles Bridge detection automatically and falls back to other supported transports where appropriate.

Security for integrations

If you're developing a wallet, ensure you never ask users to reveal their mnemonic. Use the device for signing operations and present clear UIs so users can understand what they're being asked to sign.

Headless environments

Running Bridge in headless or server environments is possible but uncommon: hardware wallets are inherently interactive and expect physical confirmation. Only use hardware in such environments with full understanding of the security tradeoffs.

Conclusion and further reading

Trezor Bridge plays an essential role in modern hardware wallet usage by providing a secure, well-scoped bridge between local hardware and web-based user interfaces. It simplifies device communication, improves browser compatibility, and helps maintain a strong security model where sensitive approvals happen on the device itself.

Quick checklist

• Download Bridge from the official source.
• Use a data USB cable; avoid hubs.
• Confirm everything on the device screen.
• Keep Bridge and firmware up to date.
• Use official libraries for integrations.

Below you'll find a curated list of useful links and official resources to help you continue learning and to download the software safely.