WebSocket Chat

A chat server built with Go and WebSockets. I made this to learn Go's concurrency patterns.

Live link: https://websocket-chat-production-8e24.up.railway.app

What it does

• Real-time messaging between users
• Shows typing indicators
• Username validation and join/leave notifications
• Caps at 50 users so the server doesn't crash
• Simple web interface included
• Messages disappear when you refresh (no database)

Running it

Clone and run:

git clone https://github.com/dax-side/websocket-chat.git
cd websocket-chat
go mod download
go run main.go

Or build first:

go build -o chat-server main.go
./chat-server

Open http://localhost:8080 in your browser. Try multiple tabs with different usernames.

How it works

The server creates a Hub that manages all connected users. When someone joins, the Hub spawns two goroutines for them: one reads their messages, one sends messages to them.

Browser ←→ Client ←→ Hub ←→ All Other Clients

Key parts:

• Hub: Coordinates everything, handles joins/leaves/broadcasts
• Client: Represents one connected user
• Goroutines: Each user gets two background workers
• Channels: How goroutines talk to each other
• Mutex: Prevents race conditions when updating the user list

Go patterns you'll see

• Goroutines for concurrent I/O
• Channels for passing messages between goroutines
• Select statements for multiplexing channels
• Mutex for protecting shared data
• WebSocket connection handling
• JSON encoding/decoding

Built with

• Go 1.22+
• gorilla/websocket package
• Plain HTML/CSS/JavaScript frontend

Settings

Change these in the code:

• Max users: 50 (in NewHub())
• Port: 8080 (in main())
• Username length: 20 chars max

License

MIT - do whatever you want with it.