Introduction
Trezor Bridge is the official browser-to-device communication service provided by SatoshiLabs for Trezor hardware wallets. It acts as a secure, lightweight bridge between a user's browser (or compatible desktop application) and their Trezor hardware device, enabling web-based wallets and services to interact with the device for signing transactions, managing accounts, and performing cryptographic operations.
Who should read this?
This guide is for crypto users who own a Trezor device, developers integrating hardware wallets into web apps, and security-conscious individuals who want a practical understanding of Trezor Bridge, how to install it, and how to troubleshoot common issues.
What is Trezor Bridge?
Core purpose
Trezor Bridge provides a standardized communication layer between the browser (which typically cannot directly access USB devices in older flows) and the Trezor device. It listens locally on a well-known port and exposes a secure API that web-based wallet interfaces (like the Trezor Wallet web app or third-party integrations) can call to interact with your hardware wallet.
How it works (high level)
- User installs Trezor Bridge on their computer.
- When a web app needs to interact with a Trezor device, it sends a request to the local Bridge service (via HTTP on localhost).
- Bridge forwards the request to the Trezor device over USB (or WebUSB when supported).
- The device prompts the user to confirm actions (PIN, passphrase, confirm transaction details on-device).
- After confirmation, the device signs the transaction and Bridge returns the response to the web app.
Bridge vs WebUSB vs Direct Browser Support
Modern browsers have introduced WebUSB and other APIs that permit direct access to USB devices. However, Bridge remains relevant for compatibility, cross-browser support, and to provide a consistent experience when direct WebUSB is not available or supported by a particular setup.
Installing Trezor Bridge
System requirements
- Windows 10+ / macOS 10.12+ / Linux (various distributions)
- USB port and a supported browser (Chrome, Edge, Firefox with proper settings)
Step-by-step install
1. Download
Obtain the installer from the official Trezor website. Always prefer the official source to avoid tampered binaries. Example links (official resources):
2. Run the installer
Follow platform-specific prompts. On Windows you may need to permit driver installation; macOS will request system permissions.
3. Verify the installation
After install, Bridge typically runs as a background process and listens on a local port (e.g., localhost:21325 historically). You can verify by visiting the Trezor web wallet and connecting your device — the site will detect Bridge if it's running.
Quick command checks (advanced)
# macOS / Linux: check process
ps aux | grep trezord
# Windows: check Services or Task Manager
Common installation pitfalls
- Antivirus or OS blocking installer — allow or create an exception for Bridge.
- Old Bridge version conflicting with a new one — uninstall old first.
- Browser caching or extensions interfering — try an incognito window or disable conflicting extensions.
Using Bridge with wallets and apps
Trezor Wallet (official web app)
Visit the official wallet interface and follow on-screen prompts to connect. The web app will talk to Bridge and ask you to confirm actions on your device.
Third-party integrations
Bridge is used by multiple wallet UIs and dApps. When connecting to a dApp, look for a prompt or modal that reads "Connect hardware wallet" or similar. Always double-check the origin of the web page and ensure it is the expected service.
Developer notes
Developers who integrate with Trezor should use the official libraries and APIs. The Bridge HTTP API is well-documented in the Trezor developer resources and repositories. Avoid crafting ad-hoc USB commands — rely on maintained libraries for safety and compatibility.
Troubleshooting
Device not detected
- Ensure Bridge is running (look for running process or restart the service).
- Try a different USB port or cable (some cables are power-only).
- Check OS-level permission dialogues — macOS and Windows may require explicit permission for USB access.
Old Bridge prompts or browser errors
If the browser reports unsupported Bridge or outdated version, download the latest Bridge installer from the official site and reinstall. Clear browser cache if problems persist.
Bridge refuses connection (port conflicts)
On rare systems another app may occupy the expected port. Restarting your computer often resolves transient conflicts. If persistent, inspect which process is listening and reconfigure or stop it.
Permissions & firewall
Corporate or strict personal firewalls may block localhost services. Allow Bridge through your firewall or consult your organization’s IT policy.
Reset flow (last resort)
As a last resort, uninstall Bridge, reboot, and reinstall the latest version. This does not affect your device mnemonic/seed which stays on the hardware — but always ensure you have your recovery seed safely backed up before performing any drastic action.
Security considerations
Bridge is a local service
Trezor Bridge runs locally on your machine and does not send your private keys off-device. It merely relays messages between the browser and the hardware device. The security model relies on on-device confirmations — the Trezor hardware must explicitly accept operations.
Best practices
- Only download Bridge from the official Trezor website.
- Keep your Bridge and device firmware updated.
- Verify web app origins — use bookmarks or type trusted addresses.
- Keep your recovery seed offline and never enter it into a computer/phone that you use daily.
- Use a strong, unique passphrase if you enable the passphrase feature.
Threat model: what Bridge can't protect against
Bridge cannot protect you if your computer is fully compromised by malware that can modify web pages or intercept user input. The Trezor device mitigates many risks by requiring on-device confirmations, but social engineering and phishing remain major threats.
Advanced topics
Bridge API and developer integration
Developers building integrations should consult the official Trezor JS libraries and protocol documentation. Using maintained SDKs reduces the risk of compatibility or security errors.
Headless / scriptable uses
For automation or advanced workflows, SatoshiLabs provides CLI tools and libraries. These are intended for power users and should be used with caution — automated signing increases exposure compared to manual confirmation on-device.
Firmware & Bridge versions
Maintain parity between Bridge versions and device firmware to avoid unusual edge-cases. If a firmware update notices a required Bridge version, apply recommended updates in the documented order.
FAQs
Q: Is Bridge required?
A: Not always. Some browsers and dApps support WebUSB or native integrations that can access devices without Bridge. Bridge remains useful for compatibility.
Q: Will Bridge take my seed?
A: No. Bridge does not have access to your seed — your private keys remain secured on the hardware device. Bridge facilitates secure messaging only.
Q: Can I run Bridge on headless servers?
A: Bridge is designed primarily for desktop OSes with interactive use. Running on headless servers is rarely practical because it expects USB-attached devices and local user interaction.
Q: How do I update Bridge?
A: Download the latest installer from the official site and run it. On some OSes the updater can handle the process automatically.
Resources & 10 Official Links
Below are ten useful official or trusted resources related to Trezor and Bridge:
Conclusion
Trezor Bridge remains an important component for a smooth, cross-platform experience when using Trezor hardware wallets with web-based services. It offers a secure relay between browser UI and device while keeping cryptographic secrets on the Trezor itself. By following recommended installation steps and security best practices, users can minimize friction and reduce risk while managing their crypto assets.
Final checklist
- Download Bridge from official Trezor resources.
- Keep firmware and Bridge up to date.
- Verify web origins and never share your recovery seed online.
- Use on-device confirmation for every sensitive action.