Trezor Bridge — The Secure Gateway to Your Device®

What is Trezor Bridge?

Trezor Bridge is an application that runs on your computer and exposes a secure local API used by web pages d native apps to interact with Trezor hardware wallets. Historically, browser security restrictions prevented web apps from directly using the USB or HID interfaces required to communicate with hardware devices. Bridge fills that gap without compromising the security model of the hardware wallet: private keys never leave the device, and all signing operations must still be confirmed on the device itself.

Why Bridge is necessary

Browsers intentionally sandbox web pages and limit access to system resources for security. While newer browser APIs (like WebUSB) try to reduce friction, they are not always consistent across browsers or platforms. Trezor Bridge provides a consistent, user-friendly, and secure interface across Windows, macOS, and Linux while maintaining the hardware-first security posture that makes Trezor devices trustworthy.

How Bridge works — a simplified flow

1. The user installs Trezor Bridge on their computer.
2. A supported web app or native application attempts to communicate with the Trezor device.
3. Bridge receives the request via a local HTTPs endpoint and forwards it to the connected Trezor hardware over USB/HID.
4. The Trezor device displays transaction details or prompts on its screen.
5. The user confirms the action on the device; the device signs the data locally.
6. Bridge relays the signed data back to the requesting app which can then broadcast transactions or otherwise process the response.

This design ensures that even though Bridge facilitates connectivity, it does not — and cannot — access private keys or sign transactions on behalf of the user without physical confirmation on the Trezor device.

Security model and privacy considerations

Trezor’s security model places the device as the root of trust. Bridge is designed to be a minimal transport layer with the following guarantees:

• Key isolation: Private keys and signing operations remain inside the Trezor hardware.
• User consent: Any sensitive operation must be reviewed and approved on the device’s screen by the user.
• Local-only communication: Bridge communicates over a local network interface (loopback). It does not open your device to remote control from the internet.
• Minimal telemetry: Bridge collects little to no telemetry by default. When network calls are required, they are limited to fetching updates or version manifests and are transparent to the user.

That said, users should practice standard safety hygiene: download Bridge only from the official Trezor website, verify checksums or signatures if available, and run Bridge on a system free of malware.

Installing & updating Bridge

The installation steps vary slightly by platform, but the general process is:

• Visit the official Trezor download page and choose the Bridge installer for your operating system.
• Run the installer and follow on-screen prompts. On macOS and Linux you may be asked to provide administrative privileges to register the Bridge service.
• After installation, Bridge runs automatically in the background and listens on a local endpoint. Most modern browsers and the Trezor Suite will detect it automatically.
• To update Bridge, either run the latest installer from Trezor’s website or allow the built-in updater to apply a patch if available. Keep Bridge up to date to benefit from security fixes and compatibility improvements.

Tip: If a web app prompts you to install or update Bridge, ensure the prompt originates from an official page before proceeding.

Troubleshooting common issues

Bridge not detected by the browser or app

• Confirm Bridge is running (check system tray/menubar or process list).
• Restart the browser or native app after installing Bridge.
• Try a different USB cable or port; some cables are power-only and do not carry data.
• On Linux, ensure you have the appropriate udev rules installed — the Bridge installer usually handles this, but manual steps may be necessary on some distributions.

Device not recognized or connection dropped

• Disconnect and reconnect your Trezor; when reconnecting, watch the device screen for prompts.
• Disable other applications that might compete for USB access (e.g., virtualization software or other wallet apps).
• Temporarily disable VPNs or firewall rules that could interfere with local loopback traffic (while ensuring you understand the security implications).

Certificate or permission errors in the browser

Bridge uses a local HTTPS endpoint. If your browser blocks the connection because of a certificate mismatch or policy, update Bridge to the latest version or consult official docs for platform-specific steps to trust the local certificate.

Developer integration & APIs

Developers building applications that integrate with Trezor can use the documented Bridge API or higher-level libraries maintained by the Trezor team. These libraries handle device discovery, message serialization, and session management so you can focus on the application logic. When integrating:

• Follow the official API contracts — avoid reverse-engineering or brittle hacks that may break with updates.
• Respect users’ privacy: do not attempt to transmit seeds, passphrases, or other sensitive material to remote services.
• Gracefully handle user rejections — users must be able to cancel signing operations without negative side effects.

Best practices & recommendations

• Only download Bridge from the official Trezor website. Double-check the domain and HTTPS lock before running installers.
• Keep your operating system, browser, and Bridge up to date to receive important security patches.
• Use official apps (like Trezor Suite) or well-known wallets that explicitly state Bridge support.
• Never enter your recovery seed into a computer or a website; recovery should only be performed on a hardware device in a secure environment.
• If you are a Linux user, consult distro-specific instructions for udev rules and permissions to minimize manual friction.

Where to get help

If you encounter persistent issues, consult the official Trezor support documentation, the Trezor community forum, or contact Trezor support directly. Include logs and a description of steps you’ve tried when seeking help — this speeds up diagnosis and resolution.