Trezor Bridge® — Connect Your Trezor to Web Browsers

Overview

Trezor Bridge® is a lightweight local application that enables secure communication between your Trezor hardware wallet and web-based applications running in modern browsers. Historically, browser constraints made direct USB communication with hardware devices inconsistent. Bridge solves this by running as a local trusted intermediary that exposes a secure, origin-restricted API to localhost, while handling native USB and HID interactions with the device. The net result: web apps can request operations (like retrieving public keys or signing data) while the cryptographic signing always occurs on the physical Trezor device, verified by the user on-device.

Why Bridge exists

Browsers intentionally sandbox web pages and restrict raw hardware access for security. A dedicated local bridge provides a stable, cross-platform method for web-based wallets and dapps to use Trezor devices without compromising the device's security model. Bridge centralizes device drivers, connection logic, and update mechanics while keeping user consent and on-device verification as the primary safety mechanisms.

Key features

Cross-platform compatibility: Works on Windows, macOS, and Linux (desktop distributions) and manages platform-specific USB/HID details.
Secure localhost API: Exposes a secure, origin-bound API to browser pages after explicit user consent.
Automatic device detection: Detects Trezor devices on connect/disconnect and routes requests to the correct device instance.
Signed firmware & updates: Supports secure update flows — check signatures and verify source before applying device-side firmware updates.
Developer tooling: Provides libraries and examples to integrate the bridge API into web apps and developer workflows.

Install & verify

Always download Trezor Bridge from the official Trezor website or verified distribution channels. Do not install unverified third-party packages. After installation:

Open the Bridge application — it runs in the background and exposes a protected local endpoint (typically on http://127.0.0.1 or a local socket).
When a web application requests device access, Bridge will prompt for permission and the browser will show a connection prompt; confirm only for trusted sites.
Verify signatures for firmware updates when the Suite or third-party tools prompt you to update a device.

How it works — technical summary

Bridge listens on a local, loopback interface and implements strict origin checks so only allowed web origins (websites you visit) can request device actions. When a web page requests a signing operation, Bridge forwards the unsigned payload to the connected Trezor device over USB/HID. The device parses the payload and displays human-readable details for user verification (addresses, amounts, contract data). Only after the user physically confirms on the device will the signature be produced and returned, at which point Bridge forwards the signed payload back to the web page for broadcasting.

Security model & best practices

Bridge is an enabling layer — it does not change the fundamental security model that private keys never leave the hardware device. However, safe operation depends on these practices:

Only allow connections from trusted websites. Deny unfamiliar origins when prompted.
Keep Bridge and device firmware up to date and verify update signatures.
Use on-device verification carefully: always confirm the address, amount, and context shown on the device — do not rely solely on UI text in the browser.
Run Bridge only on systems you control. Avoid installing on public or shared machines when performing sensitive operations.

Developer integration — quick example

Developers can use official libraries to talk to Bridge from web applications. The following is a minimal illustrative example showing how a web app may request a connection and ask the device for a Bitcoin address. This is only an outline — use official SDKs and follow their versioned APIs for production.

// Example (illustrative) JavaScript using a Trezor Web API
async function connectAndGetAddress() {
  // Request the bridge to allow the page to talk to the device
  await TrezorConnect.init({ manifest: { email: 'dev@example.com', appUrl: 'https://yourapp.example' }});
  // Acquire a BTC address on account 0
  const response = await TrezorConnect.getAddress({ path: "m/44'/0'/0'/0/0", coin: 'BTC' });
  if (response.success) {
    console.log('Address:', response.payload.address);
  } else {
    console.error('Error:', response.payload.error);
  }
}

CLI & debugging

For developers and power users, Bridge typically exposes logs and debugging endpoints. Use official command-line tools and debug flags to troubleshoot connectivity issues. Example CLI commands (illustrative):

# Check Bridge status (example)
trezor-bridge --status

# Run Bridge in verbose/debug mode for troubleshooting
trezor-bridge --log-level debug

Troubleshooting common issues

Browser cannot detect device: Ensure Bridge is running and up to date. Check that the cable is connected and the device is unlocked. Try restarting Bridge and the browser.
Permission denied errors: Confirm that you granted the web origin permission to access Bridge when prompted. Revoke and re-grant permissions if needed.
Firmware update failed: Verify signatures, ensure stable USB connection, and do not interrupt power during device firmware updates. Follow recovery instructions if an update is interrupted.
Conflicts with other applications: Some OS-level drivers or security software may interfere with Bridge. Temporarily disabling conflicting drivers or running Bridge with elevated permissions (only when necessary) can help diagnose.

Privacy considerations

Bridge acts as a local intermediary and does not transmit private keys or seed material to any external server. It may, however, connect the host to block explorers or third-party APIs if a web application requests that functionality; review privacy policies of any web apps you use. Keep local logs and debug output private — they may contain metadata about connected devices or transactions.

Enterprise & automation

Enterprises integrating large fleets of devices should treat Bridge as part of their operational security boundary. Consider hardened host environments, restricted network policies, and audited deployment flows. For automated signing in production, combine Bridge with secure orchestration patterns and human-in-the-loop confirmation when required by policy. Use multisig or HSM-backed approaches for enterprise custody rather than relying on single-device signing alone.

Legal & trademark note

Trezor and Trezor Bridge are registered product trademarks. This document is informational and not legal advice. Always follow official documentation for licensing, distribution, and trademark usage rules when building integrations or distributing software.

Conclusion

Trezor Bridge® provides a pragmatic and secure mechanism to bridge the gap between modern web applications and hardware wallets. It preserves the device-centric security model while enabling web-based workflows and developer integrations. Install only from official sources, verify updates and signatures, and always use on-device confirmations as the primary guardrail against unauthorized signing.

Quick reference: Download only from the official Trezor website. Verify checksums/signatures. Use on-device confirmation for every signing operation.