What is Trezor Bridge?
Trezor Bridge is a small, trusted background application that enables secure communication between your Trezor hardware wallet and desktop or web-based wallet interfaces. It provides a local transport layer that abstracts away differences between operating systems and browsers, allowing web applications and native clients to talk to your hardware device using a stable, well-scoped API. Bridge exists to overcome browser restrictions around direct hardware access while preserving strong security guarantees: private keys and recovery seeds remain on the device; Bridge merely forwards requests and responses between the host and the device.
Why Bridge matters
Modern browsers intentionally limit direct access to USB and HID devices for security. While new Web APIs like WebHID and WebUSB have improved capabilities, cross-browser inconsistencies and varying OS support can break the user experience. Trezor Bridge offers a consistent, maintained interface that wallet developers can rely on. It also centralizes driver and compatibility updates, reducing friction for users who want a reliable, cross-platform experience with their hardware wallet.
How Bridge works (high-level)
Once installed, Bridge runs as a local service on your machine. When a compatible wallet is opened, the wallet communicates with Bridge over a local HTTP/WebSocket-like channel. Bridge enumerates connected Trezor devices and forwards protocol-level commands to the device over USB (or HID). The device performs cryptographic operations—key derivation, signing, address generation—and prompts the user to confirm sensitive actions physically. Bridge never receives or stores private keys; its role is purely a communication facilitator.
Security model & guarantees
The security philosophy behind Bridge is simple and powerful: minimize trusted components and force user consent into the most critical operations. The following are core guarantees:
- On-device confirmations: Any operation that reveals sensitive data or signs a transaction requires explicit physical confirmation on the Trezor device.
- No secret exfiltration: Bridge does not and cannot access private keys or recovery seeds—those never leave the secure element inside the hardware wallet.
- Local-only transport: Communications between the wallet UI and Bridge are local to the machine; Bridge does not broadcast secret data over the internet.
- Integrity checks: The device validates firmware authenticity, and Bridge is distributed as signed installers to reduce tampering risk.
Installing Bridge — step-by-step
Below are concise but practical installation steps for the major desktop platforms. These steps assume you will obtain the Bridge installer from a trusted source and follow on-screen prompts during installation.
Windows
- Download the Bridge installer for Windows and run the executable.
- Allow the installer to make system changes when prompted; this registers the local service and any required device drivers.
- After installation, Bridge should start automatically. If not, find "Trezor Bridge" in the Start menu and launch it.
- Open your wallet interface and connect your Trezor. Approve the connection on the device when prompted.
macOS
- Open the downloaded .dmg and drag the Bridge app into your Applications folder.
- On first launch you may need to open System Preferences > Security & Privacy to allow the app. Approve this to let Bridge access USB/HID devices.
- Once allowed, Bridge will run in the background and respond when wallets attempt to connect.
Linux
- Choose the package that matches your distribution (.deb, .rpm) or use the provided tarball.
- Install the package with your package manager and ensure the Bridge service is enabled.
- On some distributions add a udev rule to grant non-root access to USB devices (instructions are typically included with the package).
After installing on any platform, restart your browser to ensure the web wallet can communicate with Bridge. If you use a web interface, the wallet will detect Bridge automatically and prompt you to connect.
Developer guidance & integration notes
Developers integrating Bridge should treat it as a local transport with a stable protocol surface. Key best practices:
- Always prompt users clearly and only request operations necessary for the UX flow.
- Validate device responses and handle errors defensively—don’t assume connectivity is reliable.
- Use origin checks and HTTPS for web front-ends even though Bridge is local—this prevents malicious pages from impersonating legitimate wallet UIs.
- Provide meaningful error messages when Bridge is not installed and link to installation guidance (locally hosted or within the app) instead of remote download mirrors.
Troubleshooting common issues
Connectivity problems are the most common user-facing issue. The following checklist resolves most problems:
- Try a different USB cable and avoid USB hubs when troubleshooting.
- Restart the Bridge service and the browser or wallet application.
- Confirm the device is unlocked (enter PIN) before attempting to connect.
- On macOS, check System Preferences > Security & Privacy to ensure Bridge is allowed.
- For Linux, ensure udev rules are installed so non-root processes can access devices.
Logs & diagnostics
Bridge produces diagnostic logs useful for advanced troubleshooting. When contacting support, include the Bridge version, operating system, and a brief reproduction of the steps you took. Avoid sharing any part of your recovery seed or private keys—logs should never contain secret material, but always verify before pasting logs into public forums.
Comparisons — Bridge vs browser-native APIs
There are trade-offs between helper applications like Bridge and direct browser APIs:
- Compatibility: Bridge provides consistent behavior across browsers and OS versions; native APIs may differ by browser and require conditional handling.
- Security surface: Bridge centralizes transport into a small, audited component; browser extensions or page-level code can have broader attack surfaces.
- UX: Bridge simplifies the user story—install once and feel confident across web wallets. Native APIs are evolving and may eventually reduce the need for Bridge, but adoption is incremental.
Best operational practices
To get the most secure and smooth experience with Bridge and your Trezor device, follow these practices:
- Install Bridge only from trusted, official sources and verify installer integrity when possible.
- Keep Bridge and device firmware up to date; read release notes for changes that may affect compatibility.
- Use a well-maintained machine for high-value transactions and avoid risky public environments.
- Always verify transaction details on the device screen before approving; never approve unexpected prompts.
- Keep your recovery seed offline and in secure physical storage; Bridge or any software should never request it.
Privacy & telemetry
Bridge is designed to operate locally and minimize telemetry. Depending on configuration, some telemetry or update checks may be enabled to help the project diagnose issues—users who prefer maximum privacy can opt out in settings where supported. Importantly, Bridge does not transmit private keys or seeds; telemetry is restricted to non-sensitive diagnostic data and versioning information.
Advanced topics — headless setups & automation
Advanced users and integrators may want to use Bridge in headless environments or integrate with automated tooling. This is possible but requires careful security reviews. For example, in automated signing flows, ensure legal and operational controls are in place to prevent accidental approvals. Prefer interactive approvals for any flow that results in fund movement.
FAQ
Q: Does Bridge ever see my private keys?
A: No. Bridge cannot access private keys or recovery seeds—those remain within the device’s secure element and never leave it.
Q: Can I use Bridge on multiple machines?
A: Yes. Install Bridge on any machine you trust; the security of your wallet remains tied to the physical device and the recovery seed.
Q: What should I do if the device prompts unexpectedly?
A: Disconnect the device immediately, close the wallet interface, and investigate. Unexpected prompts can indicate a misbehaving page or process. Never approve requests you did not initiate.
Closing thoughts
Trezor Bridge is a pragmatic solution that balances usability and security. It allows users to interact with modern wallet interfaces while keeping their cryptographic secrets isolated on the hardware device. By centralizing compatibility and providing a small, audited local service, Bridge helps reduce friction without compromising the core security model of hardware wallets. Follow the best practices above, keep your software and firmware updated, and always verify important actions on-device—these simple habits provide strong protection for managing cryptocurrencies with confidence.