Trezor Bridge — The Secure Gateway to Your Hardware Wallet

What is Trezor Bridge?

Trezor Bridge is a tiny background application (a native helper) that sits on your computer. When a web wallet or the Trezor Suite wants to communicate with your hardware wallet, they call Bridge locally. Bridge then talks to the hardware device over USB (or other supported transports), relays signed messages, and returns the results to the calling application.

Key responsibilities

• Provide a stable, cross-platform interface for web apps and Suite.
• Manage device discovery and keep sessions isolated to the local host.
• Relay signing requests without accessing or storing private keys.

Bridge acts as a courier — it carries messages between your app and your device but never opens the envelope.

How Bridge fits in the stack

From a high level: Browser / App ↔︎ Trezor Bridge (local) ↔︎ Trezor Device (USB). This separation ensures your secret material always stays inside the device and that the communication path is controlled by you (not a remote server).

When do you need it?

You need Bridge when using web-based services (including some browser extensions) or older Suite workflows that rely on it to talk to a plugged-in device. Modern Trezor Suite desktop builds often include the necessary connectivity, but Bridge remains essential for many browser integrations and some OS setups.

Security model — what Bridge does (and does not) do

The most important fact: Bridge never accesses or stores your private keys or recovery seed. Its role is purely to transport protocols between software and hardware. The device performs signing and displays transaction details for human confirmation.

Security guarantees

• Local-only Relay: Bridge runs on your machine and keeps traffic on the localhost interface.
• No key extraction: All cryptographic operations happen on the Trezor device.
• Session Isolation: Each connected application must request access; Bridge does not blindly expose the device to every process.

Limitations & threat model

Bridge does not protect you from local malware that actively manipulates host software or screens. It prevents remote attackers from talking to your device unless they already have local access. Human-in-the-loop verification (confirming on-device) is the final defence against malicious transaction substitution.

In short: use Bridge, but keep good host hygiene — up-to-date OS, trusted apps, and cautious habits.

Troubleshooting & tips

Device not detected?

• Check cables: Use a data-capable USB cable and avoid hubs during setup.
• Restart Bridge: Quit the Bridge service and relaunch the installer or service.
• Browser restart: Close the browser fully (all windows) and reopen — some browsers cache permissions.

Permissions prompt

Allow Bridge to open a localhost listener and access USB devices only if you downloaded it from the official source. Declining these prompts prevents device communication.

Conflicting helpers

If other wallet connectors or platform helpers are installed, they can sometimes conflict. Disable or uninstall older helpers if Bridge cannot claim the device.

Logs & support

Bridge logs can be helpful when contacting support — they show device discovery events and transport errors. Share them only with trusted support channels after redacting any personal information.

Developer notes & integrations

Developers building browser apps or integrations should treat Bridge as the local transport. For production apps, consider offering desktop alternatives (where appropriate) and always instruct users to download Bridge from the official domain. Respect user consent flows and request device access explicitly.

Best practices

• Use standard APIs and avoid workarounds that require elevated permissions.
• Prompt users clearly when a device action will require on-device confirmation.
• Fallback gracefully if Bridge is not available; provide clear installation guidance.