Introduction
Trezor Bridge is the official desktop helper application that enables secure, reliable communication between Trezor hardware wallets and browser-based apps or desktop clients. It abstracts transport differences (USB, WebHID, WebUSB) and provides a stable local API so that developers can focus on integration logic and UX rather than low-level device plumbing.
What Bridge does (and why it matters)
Bridge runs as a background process and provides a local endpoint that web apps (via Trezor Connect) and native apps can call to discover devices, request public keys, and ask the device to sign payloads. Because it runs locally, Bridge minimizes exposure to cross-origin or remote transport risks while providing a consistent developer experience across OSes.
Security model
Bridge is intentionally minimal: private keys live only on the hardware wallet and signing requests must be confirmed on-device. Bridge acts purely as a conduit: it does not store secrets, nor does it modify payloads. Developers should design app flows so that the device displays human-readable transaction details and users verify these on-device prior to approval.
Installation & setup
Users install Bridge from the official Trezor site or via package managers where available. For web developers, Trezor Connect will detect Bridge and fall back to supported transports depending on browser capabilities. On first-run, Bridge may prompt for necessary OS permissions (USB access on macOS/Linux or driver confirmation on Windows); provide clear guidance in your UI to help users enable required permissions.
Integration flow (developer view)
A typical integration uses the following steps: initialize Trezor Connect → detect Bridge availability → discover device(s) → request public key(s) → create unsigned transaction payload → send to device through Bridge for signing → collect signature(s) → assemble and broadcast transaction. The app should make the device prompt and the transaction details explicit so the user can safely confirm on-device.
Transport & compatibility
Bridge helps unify transports across browsers and platforms. Modern browsers support WebHID/WebUSB; Bridge provides fallbacks and consistent behavior for older environments. Keep your SDK versions pinned and test against supported browser versions and Bridge releases to detect regressions. Always include graceful error handling for transport failures and clear remediation steps in your UI.
Developer best practices
Prefer official SDKs like Trezor Connect instead of reinventing transport logic. Keep signing operations user-initiated, implement rate limiting on your backend, and log metadata-only telemetry (no secrets). For high-value transactions, require multi-step confirmation or multi-signer workflows.
Testing & QA
Test your integration on public testnets and with devices seeded using test-only mnemonics. Automate CI tests for transaction construction and include hardware-in-the-loop checks where possible. In CI, use flags and gating to ensure tests never accidentally run on mainnet. Maintain a small fleet of test devices with pinned firmware for reproducible regression checks.
User experience guidance
Give users simple, step-by-step pairing and troubleshooting instructions: check USB cable, confirm Bridge is running, verify browser permissions. Offer clear UI text when a device is awaiting confirmation and surface the exact message shown on-device so users can match it. Provide links to official support and firmware update pages to reduce friction.
Operational considerations
Monitor Bridge usage in aggregate (counts of device discovery, sign attempts, and transport errors) without collecting sensitive details. Track driver and firmware mismatch rates; these often explain support calls. Prepare runbooks for common issues and ensure your support team can request sanitized logs that do not contain secrets or private key material.
Firmware & updates
Firmware updates sometimes change device behavior or add new UX flows. Coordinate major app releases with firmware compatibility checks and communicate clearly to users when firmware updates are necessary. Offer an in-app check that warns users if their device firmware is incompatible with critical signing flows.
Privacy & compliance
Respect user privacy: do not transmit anything that could be used to reconstruct private keys. Maintain consent records for signing events and consider cryptographic proofs of approval if needed. If your product operates in regulated spaces, consult legal counsel on KYC/AML obligations and custody rules before offering custodial features.
Sample code (high-level)
// Example (JS + Trezor Connect)
import TrezorConnect from 'trezor-connect';
await TrezorConnect.init({ manifest: { email: 'dev@example.com', appUrl: 'https://example.com' }});
const device = await TrezorConnect.request({ method: 'enumerate' });
// Build unsigned tx on your server and return PSBT / payload
const signed = await TrezorConnect.request({ method: 'signTransaction', params: {/* psbt */} });
// Combine signatures and broadcast to the network