Tabs
Navigation, ordering, pinning, moves, and closures stay in step.
Links
Your Helium workspace, everywhere.
Relay keeps your tabs, windows, and tab groups synchronized across devices with end-to-end encryption.
Built for Helium. Also works with supported Chromium-based browsers.
Why Relay
Sync without handing over your workspace.
Browser sync usually starts with a vendor account. Relay starts with keys created on your devices.
Workspace state is encrypted before it leaves the browser, then coordinated as ciphertext through a small Cloudflare backend.
What it syncs
The shape of your session.
Relay follows the workspace structure you care about, while protected pages and device-only preferences stay local.
Windows
Multiple browser windows are recreated across your Relay devices.
Tab groups
Supported group titles, colors, membership, and structure travel together.
Offline changes
Keep working offline. Relay journals changes and reconciles on reconnect.
Device pairing
A new device joins only when you approve it.
Start setup on one device, approve it from another, then compare a six-digit code before workspace keys are shared.
Request access approve the device compare the code
Privacy by architecture
Encrypted before it leaves your browser.
Relay’s Worker assigns revisions and moves encrypted operations between devices. It does not need access to the plaintext synchronized workspace.
Read the threat model
Experimental software. Relay has not received an independent security audit.
- Workspace
- Encrypted on your device before synchronization.
- Coordinator
- Handles ciphertext and operational metadata—not your plaintext workspace.
- Revocation
- Rotates the workspace key for the devices you keep.
How it works
A relay, not a window into your browser.
Devices sign, encrypt, send, verify, and reconcile. The backend supplies ordering and coordination without holding the workspace key.
Open source, end to end
Inspect it. Host it. Improve it.
Built in public
The extension, protocol, cryptography, and Worker implementation are all in the repository.
Self-host the backend
Run the Cloudflare Worker and Durable Object under your own account and origin.
Self-hosting guideAGPL-3.0-or-later
Use, study, modify, and share Relay under its open-source license.
Read the licenseFAQ
A few useful details.
Relay is early software. These answers describe what it does today.
Is Relay made by Helium?
No. Relay was built for Helium, but it is an independent open-source project and is not affiliated with or endorsed by Helium.
Which browsers does Relay support?
Relay is designed for Helium and can work with supported Chromium-based browsers. Firefox is not currently supported.
Can the Relay server read my workspace?
Relay encrypts synchronized workspace state on your devices before sending it. The coordinator stores and moves ciphertext, though it can still observe operational metadata such as timing, sizes, revisions, and IP addresses.
What does Relay not synchronize?
Relay does not sync passwords, cookies, logins, site storage, bookmarks, browsing history, scroll position, incognito state, or protected browser pages.
Can I self-host Relay?
Yes. The backend is a Cloudflare Worker with a SQLite-backed Durable Object, and the repository includes a self-hosting guide.
Is Relay production-ready or security audited?
No. Relay is experimental pre-release software and has not received an independent security audit. Review the threat model before relying on it.
Experimental pre-release
Take your workspace with you.
Try Relay with Helium or another supported Chromium-based browser.