Trezor Bridge® — Connect Your Trezor to Web Browsers

What is Trezor Bridge?

Trezor Bridge is a small, open-source helper application developed by SatoshiLabs that creates a secure communication channel between your Trezor hardware wallet and desktop software or web-based applications. It acts as a local server that mediates USB/WebUSB requests, allowing applications — such as Trezor Suite or compatible browser extensions — to discover and talk to your device without exposing private keys.

Why a bridge is necessary

Trezor devices are purpose-built to keep private keys isolated on the device. Browsers and desktop applications cannot directly access USB hardware in a consistent, secure way across operating systems; browsers implement different security models and often limit access. Bridge provides a stable, cross-platform endpoint so apps can communicate with Trezor devices reliably. It abstracts the platform differences and ensures the cryptographic operations always occur on the hardware itself.

Core responsibilities

• USB/WebUSB shimming: Receives browser or app requests and forwards them to the connected Trezor device.
• Process isolation: Runs as a separate process on the host and never handles or stores private keys.
• Versioning & updates: Makes it easy to deploy compatibility and security patches without altering on-device firmware.

How Bridge fits into the Trezor security model

The strongest guarantees come from keeping private keys and signing on-device. Bridge complements this model: it only forwards instructions and results. All user confirmations — PIN entry, passphrase input, and transaction signing — occur on the Trezor device display and buttons (or touchscreen, depending on the model). This means even if the host computer or browser is compromised, an attacker cannot sign transactions without physical confirmation on the device.

Supported platforms & browser behavior

Bridge supports Windows, macOS, and several Linux distributions. On Windows it may install a small driver to enable access; on macOS and Linux it creates the necessary listener so that browsers and desktop apps can discover the device. Some browsers (Chrome-based and others with WebUSB support) will interact with Bridge differently — Bridge emulates the expected WebUSB endpoints for apps that depend on them.

Security design in depth

Bridge was written with a minimalist security posture. It intentionally performs no cryptographic functions and does not parse or store secrets. Its code is open-source, undergoes security review, and is published on the official Trezor GitHub: trezor-bridge on GitHub. Because Bridge mediates USB requests, it applies access control so only local applications can call it; network exposure is limited to local host interfaces by design.

Privacy considerations

Bridge does not upload your transaction data or private keys to any cloud service. Bridge may communicate with the local application and the device; some endpoints in the Trezor ecosystem may query network data (such as blockchain explorers) from the host app, but those requests are separate from Bridge itself. If privacy is paramount, review Trezor Suite settings and consider using privacy-preserving practices like running your own node for blockchain queries.

Common troubleshooting

My browser can't find my Trezor — what do I do?

Confirm Bridge is installed and running. Look for the Bridge icon in your system tray (or check running processes). Try reconnecting the USB cable, use a different port, and use the original cable provided with the device. If using macOS, confirm you granted the installer the necessary permissions in System Preferences.

Bridge reports a permission or driver error on Windows?

Run the installer as Administrator and accept the driver installation. If you previously installed a third-party driver for USB devices, remove conflicting drivers. Restart your computer after installation.

Why does my browser still prompt for WebUSB access?

Some browsers require explicit user permission for WebUSB. When prompted, allow access for the Trezor site or use Bridge which often alleviates these prompts by providing a local API endpoint for apps to connect through.

Is it safe to run Bridge on a shared or public computer?

Running Bridge on untrusted machines is not recommended. Although Bridge does not expose keys, a compromised host with full control could attempt to prompt you to sign malicious transactions. Use only trusted machines for sensitive operations, and consider keeping large holdings on a device connected to a dedicated, secured host.

Developer notes & integrations

Developers building web or desktop apps that integrate with Trezor devices should consult the official API and protocol documentation. Bridge provides a stable local endpoint that implements the expected message framing and endpoints; code samples and SDKs are available in the Trezor developer docs and GitHub repositories. When designing UX, always prompt users to verify content on the Trezor device and avoid relying solely on host confirmations.

Best practices for users

• Always download Bridge from the official site: trezor.io/bridge.
• Keep Trezor firmware and your host applications (Trezor Suite, browser) up to date.
• Verify transaction details on the device screen before confirming.
• Store your recovery seed offline and never type it into a computer or online form.
• Use a dedicated trusted computer when managing large or long-term holdings.

Advanced topics — passphrases & hidden wallets

Trezor supports optional passphrases that create additional hidden wallets derived from your recovery seed. These provide plausible deniability and an additional layer of protection, but they come with increased responsibility: losing the passphrase means losing access to that hidden wallet. Bridge does not change the semantics of passphrases — it simply forwards requests; all passphrase inputs and confirmations must occur on the device.

Where to get help & learn more

Official resources are the best first step for support and learning: the Trezor Support Center, the Trezor Blog for best practices and security advice, and the Trezor GitHub for source code and release notes. Useful links include the Trezor homepage (trezor.io), downloads (trezor.io/start), and the Bridge repository (github.com/trezor/trezor-bridge).

FAQ — quick answers

• Does Bridge store my PIN or seed? No — Bridge never stores or transmits your PIN or recovery seed.
• Can Bridge be used remotely? No — Bridge is designed for local host use and listens on loopback interfaces by default; it is not intended to be exposed to the public internet.
• Where can I verify Bridge code? On the Trezor GitHub repository: trezor-bridge.

Final thoughts

Trezor Bridge fills a small but critical role in the hardware wallet ecosystem: it provides a reliable, auditable, and updateable connection pathway between your Trezor device and the apps you trust. Because the private keys remain on the hardware and every sensitive action requires device confirmation, Bridge helps balance a polished user experience with robust security. Install only from official sources, keep your software and firmware current, and always confirm actions on your Trezor device.

Useful pages: Download Bridge • Trezor Suite • Quick start.