Owncast Chat Bridge

Bring your Owncast stream chat into Minecraft, and send Minecraft chat back to your stream.

Owncast Chat Bridge is a small server-side mod for Forge 1.20.1 and NeoForge 1.21.1 that connects your Owncast chat with in-game chat. Viewers' messages appear in-game for every player, and player messages show up in your stream chat. You don't need RCON, a separate bot, or log-tailing. Drop in the jar, fill in the config, and you're set.

Features

• Two-way chat: stream chat appears in-game, and in-game chat is posted back to Owncast.
• Viewer name colors: each chatter's name uses their Owncast color (with adjustable saturation and lightness).
• Join and leave messages: optional "name joined the chat" and "name left the chat" lines in-game.
• Filtering:
  • Block specific Owncast users.
  • Block or censor (***) words and phrases, in both directions.
  • Cap message length.
  • Replace links with <link>.
• No echo loops: messages never bounce back and forth between game and stream.
• Server-side only: players don't need to install anything.
• Lightweight: it uses Java's built-in HTTP server and adds no extra dependencies.

Requirements

You also need an Owncast server you can administer.

The server must run on a full JDK, not a stripped-down runtime. Standard server installs and hosting panels already use one.

Setup

1. Install

Put the jar for your loader in your server's mods/ folder, start the server once to generate the config, then stop it.

2. Create an Owncast access token (for game → stream)

In Owncast admin, go to Integrations → Access Tokens → Create Access Token. Give it the Send chat messages scope and copy the token.

3. Configure

Edit config/owncastbridge-common.toml:

[owncast]
    baseUrl = "http://localhost:8080"   # your Owncast server, no trailing slash
    accessToken = "PASTE_YOUR_TOKEN"

[webhook]
    port = 8100                         # port this mod listens on
    secret = "some-long-random-string"  # optional but recommended

[relay]
    streamToGame = true
    gameToStream = true
    streamPrefix = "[Stream] "

The config also has sections for [colors] (name colors), [events] (join and leave lines) and [filter] (blocked users and words, link stripping, length limit). Each option is commented in the generated file.

4. Point Owncast at the mod (for stream → game)

In Owncast admin, go to Integrations → Webhooks → Create Webhook and use this URL:

http://<minecraft-server-host>:8100/owncast?secret=some-long-random-string

Turn on these events:

• When a user sends a chat message (required)
• When a user joins the chat (optional, for join lines)
• When a user leaves the chat (optional, for leave lines)

If Owncast runs on a different machine, make sure port 8100 is reachable from it (firewall or port forward). If you left secret blank, drop the ?secret=... part.

Start the server. Stream chat now shows up in-game as [Stream] username: message.

FAQ

Does it work in singleplayer? Yes.

Join and leave lines are spammy. Owncast sends these whenever a viewer's chat connection opens or closes, and that includes page refreshes. Turn off showJoins or showLeaves in [events] to hide them.

The server won't start after adding the mod. Check that you used the jar for your loader and Minecraft version. NeoForge 1.21.1 also needs Java 21; Java 17 won't load it.

I get NoClassDefFoundError: com/sun/net/httpserver/.... Your server is running on a stripped-down Java runtime. Run it with a full JDK (17+ for Forge 1.20.1, 21+ for NeoForge 1.21.1).

Fabric or other Minecraft versions? Not right now. Only Forge 1.20.1 and NeoForge 1.21.1 are supported.

Licensed under MIT.