Overview

Trézór Bridge®™ is a lightweight local service designed to provide secure, reliable connectivity between a hardware cryptocurrency wallet and web-based interfaces. As browsers tighten direct USB access for safety, a small, trusted helper running on the user's machine becomes necessary to mediate communication. Bridge performs that role: it listens on a local loopback interface, forwards requests from trusted web applications to the hardware device, and returns signed responses back to the webpage. It is intended to be minimal, auditable, and local-only so it complements the hardware wallet's security posture rather than replacing it.

Why Trézór Bridge exists

The web platform changed. Browser vendors deprecated many legacy extension APIs and tightened the rules around direct USB or HID access. While these changes reduced broad attack surfaces, they created friction for users who need to connect hardware devices from within the browser. Trézór Bridge exists to restore predictable, cross-browser connectivity while keeping the security model intact.

Key motivations include:

• Compatibility: Bridge runs at the OS level, so it is less brittle than a browser extension and works across Chromium, Firefox and other browsers that may vary in USB support.
• Reliability: Device detection becomes consistent; Bridge reduces instances where a site cannot find a plugged-in hardware wallet.
• Security hygiene: Bridge confines communication to the local host, ensuring there is no remote network exposure.
• Developer ergonomics: Web apps can rely on a stable local endpoint rather than implementing multiple browser-specific fallbacks.

Architecture & how it works

The architecture is intentionally simple and purpose-driven. Bridge consists of a small background process that listens on a loopback address (for example, http://localhost:xxxx). When a web application needs to talk to the hardware wallet, it sends a request to this local host endpoint. The Bridge then performs the necessary USB/HID calls to the device, receives the device's responses, and relays them back to the web application.

Communication flow

1. The user connects the hardware wallet to the computer using USB.
2. The user opens a Trezor-aware web app (for example, a web wallet or Trézór Suite Web).
3. The web app makes a request to the Bridge service on localhost.
4. Bridge translates the request into USB/HID operations and communicates with the device.
5. The hardware device displays transaction or action details and prompts the user to confirm on-device.
6. After the user confirms, the device signs or returns the requested data; Bridge relays that response back to the web app.

The crucial security point is that the device performs all cryptographic operations internally; Bridge only transports non-secret data and signed results. The device screen is the authoritative interface for confirming any action involving private keys.

Installation — step-by-step

Installation should always be performed using official download links to avoid counterfeit or tampered packages. Below are general platform steps and notes.

Windows

Download the official installer, run it, and follow the prompts. The Bridge runs as a small background service. After installation, restart your browser and plug in your device. If detection fails, try replugging or running the installer as Administrator.

macOS

Download the macOS package, drag the app into /Applications, and run it. macOS may require explicit approval in System Settings → Privacy & Security. Grant permission for the helper to run if prompted and restart your browser.

Linux

Install the provided DEB/RPM package or tarball. Ensure udev rules are installed so non-root users can access USB devices. After installation, log out and back in or reboot to apply permissions.

Notes

The Trézór Suite desktop application often communicates with the hardware directly and may remove the need for Bridge. WebUSB is an alternative in browsers that support it, but Bridge remains the most reliable cross-platform fallback.

Usage patterns & integrations

Bridge is useful whenever you need to interact with your hardware wallet from within a browser. Typical use-cases include:

• Trezor Suite Web: account management, address generation, balance checks.
• Browser-based wallets and dApps that support hardware wallets for signing transactions.
• Third-party web services that rely on on-device signing to maintain custody guarantees.

In multi-app scenarios, ensure only one application is attempting to access the device at a time — concurrent access attempts can create conflicts. Developers building integrations should always present clear on-device verification details and fallback to Bridge gracefully when WebUSB is unavailable.

Security model & guarantees

Trézór Bridge®™ is designed so that it does not alter the hardware wallet's security guarantees. The device remains the root of trust; Bridge is a conduit, not a custodian.

Core properties

• Secrets never leave the device: Private keys, seeds, PINs, and passphrases are generated and stored on the hardware and never transmitted to the host or Bridge.
• Local-only communications: Bridge listens on localhost (loopback). It does not open remote network ports and is not reachable from external networks.
• Manual confirmation: All critical operations require physical confirmation on the device display; attackers cannot remotely approve transactions.
• Auditable codebase: Bridge and related components are designed to be minimal and reviewable to encourage audits and community scrutiny.

Practical security tips

• Download Bridge only from the official source.
• Keep both the hardware device firmware and Bridge updated.
• Use a high-quality USB data cable and avoid public or untrusted machines for signing critical transactions.
• Always verify addresses and amounts on the device’s screen before confirming.

Troubleshooting common issues

While Bridge is stable, users can encounter connectivity problems. Here are common symptoms and remedies.

Device not detected

• Confirm Bridge is installed and running — check for a system tray icon or the process list.
• Restart the browser after installation and replug the device.
• Try a different USB port or a known-good cable; some cables are power-only.

Device detected but actions fail

• Ensure your device firmware is up to date using the desktop Suite if possible.
• Close other apps that may be accessing the device simultaneously.
• Reboot the host machine to clear driver issues or stale locks.

Bridge won't start

• Reinstall from the official site and restart your computer.
• On macOS or Windows, check system-level security prompts and allow the app to run if blocked.
• On Linux, verify that udev rules are present and active.

If problems persist, use official support channels and documentation instead of third-party "fixes" which can introduce risk.

Best practices & daily habits

Adopting a few consistent practices makes daily use of Bridge and your hardware wallet smooth and safe:

• Prefer the desktop Suite for firmware updates and high-value operations.
• Keep Bridge and Suite versions current — browsers sometimes require patched helpers after major updates.
• Limit simultaneous connections and avoid running multiple wallet apps at the same time.
• Perform a small test transaction when integrating with new services to confirm workflow correctness.
• Store recovery seeds offline and treat them as the single most critical secret; never photograph or upload them.

Conclusion

Trézór Bridge®™ provides a secure, pragmatic solution to the modern problem of connecting hardware wallets to web applications. By running locally, remaining minimal, and preserving the device as the signing authority, Bridge restores browser-based usability without compromising custody guarantees. Whether you use Trézór Suite web, third-party dApps, or developer tools, installing and maintaining Bridge ensures a consistent, trustworthy experience. Follow the security guidance above — download only from official sources, verify on-device, keep software updated, and use desktop tools for critical tasks. If you prefer to avoid Bridge, native desktop suites provide an alternative path, but for many web workflows Bridge remains the most practical and safest option.