Trezor Bridge — Secure Connection for Your Trezor

What is Trezor Bridge?

Trezor Bridge is a lightweight, locally running service that provides a stable and secure channel between Trezor devices connected by USB and wallet applications in your browser or on the desktop. Rather than exposing raw USB access to web pages (which is inconsistent across browsers and operating systems), Bridge provides a predictable API and event flow, improving reliability and security for users and developers alike.

Why Bridge exists

Modern browsers restrict direct USB access to web pages for good reasons. Those restrictions, combined with differing OS USB stacks, created an inconsistent experience for hardware wallet users. Trezor Bridge solves this by running a trusted helper on the user's machine that accepts authenticated local requests from approved apps and forwards them to the connected device. This avoids browser quirks and keeps private keys inside the Trezor device at all times.

How Bridge works (high-level)

When you open a compatible wallet app, the app sends a request to a predefined local port or endpoint where Bridge listens. Bridge detects connected Trezor devices, negotiates USB access, and then forwards commands and responses between the app and the hardware. The device performs all sensitive cryptographic operations on-device and displays prompts to you for confirmation. Bridge itself does not store keys or seed phrases.

Key features

Installing Trezor Bridge

Always download Bridge from the official Trezor domain. Installation steps vary by OS:

1. Windows: Run the installer, allow driver installation when prompted, and restart your browser after the install completes.
2. macOS: Run the signed installer, and if the OS blocks it, open System Preferences → Security & Privacy to allow the installation.
3. Linux: Use the provided packages or distribution-specific instructions. You might need to add udev rules or user permissions to allow USB access without sudo.

First-run checklist

• Verify you downloaded the installer from trezor.io and check the digital signature or checksum where available.
• Install, then reboot your browser (or the whole OS) to ensure the app discovers Bridge.
• Connect your Trezor device with a data-capable USB cable (some thin cables are power-only).
• Open Trezor Suite or a compatible web wallet — your device should be listed automatically.

Security considerations

Bridge is designed to minimize risk but it is still software running on your machine. Here are layered defenses and recommended practices:

• Official sources only: download Bridge from trezor.io and verify checksums or signatures where available to avoid tampered installers.
• Keep your OS updated: security patches reduce the risk of local exploits that could attempt to intercept Bridge traffic.
• Verify on-device prompts: never approve a transaction or action without confirming details on the Trezor screen; the device is the last line of defense.
• Limit trusted applications: do not grant hardware access to unknown browser extensions or untrusted web apps.
• Firewall rules: Bridge listens locally — you can restrict its network exposure further with OS firewall rules if desired.

Troubleshooting common problems

1. Device not detected: ensure Bridge is running (look for the process in your task manager), reconnect the cable, try different USB ports, and use a data-capable cable.
2. Browser doesn't see device: restart the browser, clear site data, and confirm Bridge is allowed to accept local connections.
3. Installer blocked: on macOS open Security & Privacy and allow the installer; on Windows check driver prompt messages.
4. Permission issues on Linux: add the recommended udev rules or run Bridge under a user with appropriate USB permissions.
5. Still failing: fully uninstall Bridge, reboot, and reinstall the latest release from the official site.

Bridge vs. WebUSB: Which should you use?

WebUSB is a browser API that allows web pages to talk to USB devices directly. It can work well in some setups, but support and behavior vary across browsers and operating systems. Trezor Bridge provides a more consistent, tested interface across environments and helps avoid many compatibility quirks. For this reason, Bridge is recommended for users who want a stable, cross-platform experience; WebUSB may be used as an alternative in environments where it's fully supported.

Developer notes

If you're building integrations:

• Consult the official Trezor API documentation for request formats, error handling, and recommended security patterns.
• Use well-defined feature-detection and fallback paths: check for Bridge, then WebUSB support, then document how the user can install Bridge if necessary.
• Sign and version your integrations; make clear to users when a bridging helper is required.
• Respect user privacy: do not log seed material or keep unnecessary long-term local records of transactions.

Advanced workflows

For users with specialized security setups, Bridge can be combined with air-gapped signing and offline workflows. For example, you may generate unsigned transactions on an offline machine and use Bridge-assisted flows on a different machine for device detection and signing — depending on your operational security needs.

FAQ

Final thoughts

Trezor Bridge is a small but important piece of the Trezor ecosystem: it smooths the user experience, bridges platform differences, and keeps sensitive operations on the device where they belong. For most users, installing Bridge from the official site and following basic security hygiene is the right trade-off between convenience and safety. Developers benefit from a stable local API, and security-minded users can combine Bridge with air-gapped practices when needed.