Trezor Bridge — The Secure Gateway to Your Hardware Wallet®

What is Trezor Bridge?

Trezor Bridge is a small, local background application that provides a secure communication layer between browser-based applications (web wallets, decentralized apps) and Trezor hardware wallets connected to your computer via USB. It exposes a controlled, localhost API that web apps can use to discover devices, read public addresses, and request signatures. Bridge is a mediator — it never accesses private keys or recovery seeds. All sensitive cryptographic operations happen within the secure hardware of the Trezor device itself, and every signing action requires explicit confirmation on the device's screen.

Why Bridge exists

Browsers intentionally limit direct hardware access for security reasons, and different browsers implement USB and security policies differently. Rather than relying on browser-specific extensions or direct USB calls, Trezor Bridge provides a unified, well-maintained, and auditable interface. This makes it easier for developers to integrate Trezor support into web apps and for users to connect their devices across operating systems and browsers without complicated installation steps.

In short, Bridge solves compatibility and user-experience challenges while keeping the trust boundary firmly on your hardware device.

Download and install Bridge (safe steps)

1. Open your browser and go to the official Trezor start page at trezor.io/start. Type the URL manually or use a trusted bookmark to avoid phishing.
2. Choose the Trezor Bridge installer for your operating system (Windows, macOS, Linux) and download the package.
3. Optionally verify the file checksum or signature if Trezor publishes one — advanced users can use this to confirm the download's integrity.
4. Run the installer and grant any required system permissions. On Windows Bridge runs as a service; on macOS/Linux follow the platform prompts to start the Bridge daemon.
5. After installation, look for the Bridge icon in your system tray or menu bar — Bridge typically runs silently in the background and listens on localhost for incoming requests from the browser.

Always download Bridge from the official domain (trezor.io). If an installer behaves unexpectedly (unknown publisher, unusual prompts), stop and verify the source.

How Bridge works (technical overview)

Bridge exposes a local HTTP and WebSocket API. Web pages using Trezor interact via an official client library that takes care of message formatting, origin checks, and user flow. When a web app requests an operation — for example, to retrieve a public address or request a transaction signature — the library sends that request to Bridge. Bridge forwards the request to the connected Trezor device over USB. The device displays the crucial information (address, amount, destination, data) on its screen and asks the user to confirm. Only after on-device approval will the device return signed data back through Bridge to the web app.

This layered approach preserves several critical safeguards:

• Local-only binding: Bridge listens on localhost, preventing remote network access.
• Origin validation: Client libraries and Bridge perform origin checks to ensure requests come from the expected web page.
• On-device confirmation: Every signing operation requires manual approval on the Trezor device screen — the final authority.

Using Bridge with web3 apps — typical flow

1. Open a web3-compatible site (a dApp or web wallet) that supports Trezor and choose to connect a hardware wallet.
2. If Bridge is not installed, the site usually prompts you to install it; follow official install instructions from trezor.io.
3. With Bridge running, plug in and unlock your Trezor device by entering your PIN on the device.
4. If the web app requires a specific chain app, open the relevant app on your Trezor (e.g., Ethereum app) when prompted.
5. Approve the connection and, later, review and confirm each signing request on-device. Don’t approve anything you don’t recognize.

Always verify critical details — destination addresses, amounts, and data — on the Trezor screen before approving. The device display is the canonical source of truth.

Security model & best practices

Bridge is explicitly designed to minimize risk, but user behavior and system security still matter. Follow these best practices:

• Install Bridge only from trezor.io and keep it updated through official prompts.
• Apply firmware updates to your Trezor device only via official channels (Trezor Suite) and verify on-device prompts during updates.
• Verify webapp domains before connecting. Phishing dApps can mimic legitimate apps to trick users into signing malicious transactions.
• Use a trusted, up-to-date computer for sensitive operations. Consider a dedicated machine for high-value transactions.
• Never type your recovery seed into a website or any software — only enter it on the device during official recovery procedures.

Bridge does not and cannot access private keys or recovery seeds. However, a compromised system or malicious webpage could attempt to misuse Bridge; on-device confirmations are the last line of defense.

Privacy, permissions and what Bridge sees

Bridge functions locally and typically does not send personal data over the network. That said, when you use web apps, those apps may record addresses, transactions, and metadata. Consider the following privacy precautions:

• Use separate browser profiles for sensitive crypto activity to reduce cross-site tracking.
• Clear cookies and site data after performing sensitive operations if you’re concerned about local traces.
• Assume that any connected web service can observe transaction metadata you submit to it — minimize data exposure where possible.

Developer guidance

If you’re building a web3 app that integrates Trezor, follow these guidelines:

• Use the official Trezor client libraries (Trezor Connect) instead of calling Bridge directly. The libraries handle origin checks, UX flows, and compatibility details.
• Request only the permissions you need and clearly explain why each permission is required.
• Provide clear UI explaining what the hardware device will prompt for, and show users readable transaction summaries before requesting signatures.
• Implement robust error handling for device disconnection, Bridge missing, and user cancellations.
• Test across browsers and platforms, and document expected behaviors and fallbacks for users who lack Bridge.

Keeping dependencies updated and following secure coding practices reduces the chance of supply-chain vulnerabilities affecting your integration.

Troubleshooting common Bridge issues

Browser does not detect Bridge

• Ensure Bridge is running (check for the tray/menu icon) and restart the browser.
• Restart the Bridge service if necessary, and check firewall settings that may block localhost ports used by Bridge.
• Reinstall Bridge from trezor.io/start if detection fails repeatedly.

Device not recognized

• Try a different data-capable USB cable and connect directly to the computer (avoid hubs).
• Unlock the device by entering the PIN on the hardware and open the required chain app if requested.

Origin or permission errors

If you see origin mismatch warnings, verify the web page domain and ensure you are on the official site or a trusted dApp. Cancel the request if anything appears suspicious.

Frequently asked questions

Does Bridge store my private keys?

No — Bridge never has access to private keys or recovery seeds. It is a forwarding mechanism that relays requests between the browser and the hardware device. Signing takes place on-device only after your explicit approval.

Can I use Trezor without Bridge?

Yes. You can use Trezor Suite (desktop) or native integrations that do not depend on Bridge. Bridge is primarily helpful for browser-based dApp support.

Is Bridge open source?

Parts of the Trezor ecosystem are open source. Check the official Trezor GitHub repositories for available source code, client libraries, and developer documentation.