Building Aegis: an anonymous chat app with no database

Aegis is deliberately small. There's no sign-up, no password, and no database — you pick a display name, join or create a room, and start talking. Here's the shape of it.

No accounts, just a name

The entire "auth" flow is a single socket event:

@SubscribeMessage('setUsername')
handleSetUsername(client: Socket, username: string) {
  this.service.registerUser(client.id, username);
}

That's it. The identity is tied to the socket connection, not a stored credential. When the client reconnects — say, after the server restarts — it just re-emits setUsername and picks up where it left off.

State lives in a Map, not a database

Rooms, messages, and typing indicators are all plain Map and Set instances inside a single ChatService. That means:

• Zero infrastructure to run besides the NestJS process itself.
• Everything resets on restart — which is fine for ephemeral, throwaway conversations.
• Adding persistence later is a contained change: one service, one clear seam.

Why keep it this way

Aegis was never meant to be a durable chat platform — it's meant to be the kind of thing you can open, use for two minutes, and close. Keeping it stateless (aside from the in-memory room data) is what let it become a "free tool" bolted onto a much larger site without dragging in a database migration or an auth system that would have to interoperate with everything else here.