Trezor Bridge

Introduction to Trezor Bridge

In the world of cryptocurrency security, the connection between your offline hardware wallet and the online world is critical. Trezor Bridge serves as this vital link. It is a lightweight communication tool designed specifically to facilitate the interaction between your Trezor hardware device and supported internet browsers.

Without this bridge, your browser—which operates in a sandboxed environment for security—cannot directly communicate with USB devices connected to your computer. Trezor Bridge solves this by running in the background and creating a secure local server that your browser can talk to, which then relays commands to your Trezor device.

What is Trezor Bridge?

Technically speaking, Trezor Bridge is a standalone application known as trezord. It runs as a background process on your operating system (Windows, macOS, or Linux). Unlike browser extensions that can be vulnerable to specific browser exploits, Trezor Bridge operates at the system level, providing a more robust and consistent communication channel.

Originally, Trezor used a Chrome extension for this purpose. However, as browser technologies evolved and Google phased out Chrome Apps, the need for a more permanent and browser-agnostic solution became apparent. Trezor Bridge was developed to fill this gap, ensuring that users can access their wallets regardless of browser updates or policy changes.

How Trezor Bridge Works

When you install Trezor Bridge, it sets up a local server on your machine, typically listening on port 21325. This local server is only accessible from your own computer (localhost), ensuring that no external parties can connect to it.

The communication flow works as follows:

1. You visit a Trezor-compatible website (like Trezor Suite for Web or a third-party wallet like MyEtherWallet).
2. The website sends a request to http://127.0.0.1:21325/.
3. Trezor Bridge receives this request and checks if a Trezor device is connected via USB.
4. If connected, the Bridge translates the web request into USB commands that the hardware wallet understands.
5. The hardware wallet processes the command (e.g., signing a transaction) and sends the result back to the Bridge.
6. The Bridge relays this result back to the browser window.

This entire process happens in milliseconds, providing a seamless user experience. Crucially, your private keys never leave the Trezor device during this process. The Bridge only transports public data and signed transaction data, never the secrets themselves.

Installation Guide

Installing Trezor Bridge is straightforward. It is compatible with all major operating systems. Follow these steps to ensure a secure installation:

System Requirements

• Windows: Windows 10 or later (64-bit recommended)
• macOS: macOS 10.15 (Catalina) or later
• Linux: Most modern distributions (Ubuntu, Fedora, Debian) - 64-bit required

Step-by-Step Installation

Troubleshooting & Maintenance

While Trezor Bridge is designed to be "install and forget," you may occasionally encounter issues where your device is not detected. Here are common solutions.

Bridge Not Running

If the Trezor Wallet website says "Bridge not installed" even after you installed it, the background process might have stopped.

• Open your Task Manager (Windows) or Activity Monitor (macOS).
• Look for a process named trezord or trezord-go.
• If it's not there, try launching the application manually from your applications folder, or reinstall it.

Port Conflicts

Trezor Bridge uses port 21325. If another application is using this port, the Bridge cannot start. This is rare but can happen with some development tools. You can check the status by visiting http://127.0.0.1:21325/status/ in your browser. You should see a JSON response if it is working correctly.

Clearing Browser Cache

Sometimes the browser holds onto an old state. Clearing your browser's cache or trying an Incognito/Private window can force the browser to re-establish a connection with the Bridge.

Security Architecture

Security is the paramount concern for any crypto-related software. Trezor Bridge is built with several security layers:

• Code Signing: All official binaries are cryptographically signed by SatoshiLabs. Your operating system verifies this signature before installation.
• Localhost Restriction: The Bridge only listens to requests from the local machine. It does not expose your device to the wider internet.
• Minimal Data Handling: The Bridge does not interpret the transaction data; it acts purely as a conduit. The interpretation and signing happen strictly within the hardware wallet.
• Open Source: The code for Trezor Bridge is open source, allowing security researchers to audit it for vulnerabilities constantly.

It is important to note that while the Bridge secures the transport layer, you must still verify all transaction details on the physical screen of your Trezor device. The computer screen can be manipulated by malware, but the Trezor screen cannot.

Trezor Bridge vs. Trezor Suite

Users often get confused between Trezor Bridge and Trezor Suite. Here is the distinction:

Trezor Suite is the full-featured interface (available as a desktop app or web app) where you manage your portfolio, send transactions, and view balances.

Trezor Bridge is the driver-like software that allows the Web version of Trezor Suite to talk to your device.

If you use the Trezor Suite Desktop App, the Bridge is actually built-in internally, so you don't strictly need to install the standalone Bridge. However, having the standalone Bridge installed is recommended as it allows you to use your Trezor with other web-based wallets (like MetaMask, MyCrypto, or Yoroi) without issues.