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Pion WebRTC
Offline Browser Sync

WebRTC without a signaling server!

Pion webrtc Slack Widget
License: MIT

This repo demonstrates how you can connect two WebRTC proccesses without signaling. No configuration is needed ahead of time, so no hardcoding of IP Addresses. The peers use mDNS to connect to each other, and have pre-set ICE Credentials and DTLS Certificates.


  • git clone
  • cd offline-browser-communication
  • go run *.go
  • Open

You should see the following in your terminal.

Ready to connect, please load
Connection State has changed checking
Connection State has changed connected
DataChannel foo has opened

If everything worked you can now send messages from your browser to your terminal!

What this means

This means you can have two devices connect without any setup. No need to setup a server, or native apps with more control.

You could build stuff like.

  • Sync data between two PWA without a backend
  • Have a multiplayer game that never leaves your network
  • Build a conferencing/chat app that doesn't require any setup
  • Please share your cool ideas with us!


Is this secure?

No currently everything is hardcoded, this is just a demonstration. I believe this could be reasonably secure if seeded properly. Better to ask a security person though.

What platforms are supported?

OSX and Linux

What browsers work?

Only Chromium so far. If there is interest I would like to support more

What libraries/dependencies does this use

Only Pion WebRTC it is a full Go implementation of WebRTC. It has zero C/C++ usage.

What is next?

I would like to get this into the IETF/W3C, but as an individual I am unable to be involved. If you are interested and have membership please reach out!

I want to talk about cool WebRTC stuff!

Join the Pion Slack

I need to update the DTLS Fingerprint

If you see an error like InvalidAccessError: x509Cert expired the certificate has expired. You can update it by following these instructions. Please submit a PR with the updated certificate as well, thanks!

  // Create new certificate
  go run `go env GOROOT`/src/crypto/tls/generate_cert.go --host=localhost --ecdsa-curve=P256

  // Create new fingerprint for jsfiddle
  openssl x509 -noout -fingerprint -sha256 -inform pem -in cert.pem


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MIT License - see LICENSE for full text


Demonstration of a browser connecting to Pion WebRTC without a signaling server.






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