Teaching the Web new Tricks

Distributed Web Apps

We are pretty happy to share what we've been working on with Beaver to expand the Web: transparent distributed Web apps!

The Web has some messaging primitives, such as the BroadcastChannel and Message Ports. If we focus on BroacastChannel, we find that it's a simple to use gossip messaging API that will ensure that all the browsing context from a given origin can communicate. The app developer doesn't have to deal with access control, it's all managed by the web runtime.

In a regular browser, you can use BroadcastChannel between multiple tabs, in the same chrome window or not. Pretty cool, but also quite limited in today's world where most people use their browser on multiple devices. So... can we extend that capability to be distributed on multiple devices? This is exactly what we did! This relies on a few building blocks:

• We use the Iroh peer to peer framework to implement two protocols: a pairing protocol and a framed packets messaging protocol. The messaging one is only usable between paired peers.
• A new "Pairing" Web API let the system app (since in Beaver everything is Web based) manage the discovery if peers and the pairing flow.
• We don't expose a new Web API for messaging: instead, we added support in Servo's implementation of BroadcastChannel to also register paired peers channels per origin and route messages across devices.

That let web apps that use BroadcastChannel work on multiple devices, without any new API to learn for app developers! This expands naturally from multiple tabs, multiple windows to multiple devices... pretty neat, right?

Since Beaver's UI is also a Web app, we can use that new capability in Beaver itself! That's what we did with a simple use case first: we added a context menu entry that offers to open the current page on a remote paired device.

Check the video below for a quick demonstration with 2 peers:

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Updated Mar 16 2026