What is Trezor Bridge?
Trezor Bridge is a lightweight, trusted service that functions as the communication layer between a Trezor hardware wallet and applications running on your computer or in your browser. It replaces older browser plugins and unsafe direct USB access by providing a small, secure, system-level process that handles device discovery, message routing, and encryption handshakes. The Bridge's job is intentionally narrow: it transmits commands and responses while ensuring the hardware device — which stores your private keys — remains the single point of truth for signing and authorizing sensitive operations.
Why the Bridge is important
Modern browsers restrict direct USB access for good reasons; they also have historically relied on plugins or experimental APIs that can introduce security risk. Trezor Bridge fills that gap with a predictable, auditable piece of software that developers and users can trust. Because the Bridge runs outside the browser sandbox, it can manage USB and WebUSB interactions consistently across operating systems and provide stable integration for wallet apps, exchanges, and decentralized applications that require hardware-backed key signatures.
Core design principles
Trezor Bridge follows a few simple but critical principles: minimal attack surface, transparent communications, and strict separation of duties. All sensitive cryptographic operations occur on the hardware device; the Bridge never generates or stores private keys. Communications are encrypted and authenticated to guard against tampering, and the service validates application requests to ensure they match expected patterns. The result is a small trusted piece of infrastructure that can be independently reviewed and updated when necessary.
Cross-platform compatibility
The Bridge supports Windows, macOS, and Linux, and provides a consistent API for applications. It handles platform-specific USB quirks and abstracts them away from client applications, reducing integration complexity and preventing platform-specific bugs from exposing users to unnecessary risk.
How it works — a simplified flow
When you connect a Trezor device and open a compatible application (for example, Trezor Suite or a web wallet), the Bridge detects the hardware and establishes a secure channel. The application sends a transaction or request to the Bridge, which forwards it to the device. The device displays the details (addresses, amounts, fees) on its screen, and you confirm with a physical button or touch. The device then signs the transaction and returns the signature through the Bridge back to the app for broadcast. At no point does the private key leave the device.
Encrypted Channels
All messages between the host app, Bridge, and device are encrypted and authenticated to prevent interception and replay attacks.
Device Authentication
The Bridge and device perform mutual checks to ensure they are communicating with genuine counterparts. This prevents rogue devices or tampered software from masquerading as a Trezor.
No Key Exposure
Private keys remain in the secure hardware element. The Bridge only transports requests and signatures — never raw secrets.
Automatic Updates
The Bridge can be updated to address security fixes and compatibility improvements; official installers are signed to preserve integrity.
Installation & best practices
Always install Trezor Bridge from the official Trezor website and verify the installer signature when possible. Keep Bridge updated and avoid unofficial builds. When using browser-based wallets, prefer the official Trezor Suite or trusted partners and validate URLs carefully to avoid phishing. If your application cannot detect the device, check the Bridge status (it usually runs as a background service) and confirm that your USB cable supports data — some cables only provide power.
Security considerations
Although Bridge reduces risk compared to ad-hoc USB access, security depends on proper operational hygiene. Keep your OS patched, run reliable antivirus/antimalware, and never enter your recovery seed into a computer. Use the device screen for verification every time you sign a transaction, and refuse any prompts that display unexpected addresses or amounts. Additionally, enable automatic updates for the Bridge and your Trezor device firmware to benefit from the latest protections.
Troubleshooting common issues
If the Bridge fails to detect a device: restart the Bridge service, try a different USB port or cable, ensure the device is powered and unlocked, and confirm that no other applications are blocking the port. On macOS and Windows, security or privacy settings may