diff --git a/src/auth.ts b/src/auth.ts
index 3ba9414..a8cace2 100644
--- a/src/auth.ts
+++ b/src/auth.ts
@@ -15,6 +15,13 @@ if (jwtSecret === "[generic token]") {
     process.exit(1);
 }
 
+export function getPublicUserObject(user: User) {
+    const newUser = { ...user };
+    newUser.password = undefined;
+    delete newUser.password;
+
+    return newUser;
+}
 
 export function signToken(userId: number) {
     return new Promise((resolve, reject) => {
@@ -99,10 +106,7 @@ export function authenticateRoute() {
             }
 
             req.user = user;
-            req.publicUser = {...user};
-            if (req.publicUser.password) {
-                delete req.publicUser.password;
-            }
+            req.publicUser = getPublicUserObject(user);
             next();
         };
 
diff --git a/src/gateway/gatewaypayloadtype.ts b/src/gateway/gatewaypayloadtype.ts
index 4b1bee9..6c848c3 100644
--- a/src/gateway/gatewaypayloadtype.ts
+++ b/src/gateway/gatewaypayloadtype.ts
@@ -1,5 +1,6 @@
 export enum GatewayPayloadType {
     Hello = 0,
     Authenticate,
-    Ready
+    Ready,
+    Ping
 }
diff --git a/src/gateway/index.ts b/src/gateway/index.ts
index 2882d4d..76a2b9f 100644
--- a/src/gateway/index.ts
+++ b/src/gateway/index.ts
@@ -1,7 +1,8 @@
 import { Server } from "node:http";
 import { performance } from "node:perf_hooks";
-import WebSocket, { WebSocketServer } from "ws";
-import { decodeTokenOrNull } from "../auth";
+import { WebSocketServer, WebSocket } from "ws";
+import { decodeTokenOrNull, getPublicUserObject } from "../auth";
+import { query } from "../database";
 import { gatewayErrors } from "../errors";
 import { GatewayPayload } from "../types/gatewaypayload";
 import { GatewayPayloadType } from "./gatewaypayloadtype";
@@ -9,8 +10,57 @@ import { GatewayPayloadType } from "./gatewaypayloadtype";
 const GATEWAY_BATCH_INTERVAL = 25000 || process.env.GATEWAY_BATCH_INTERVAL;
 const GATEWAY_PING_INTERVAL = 20000 || process.env.GATEWAY_PING_INTERVAL;
 
+// mapping between a broadcast id and a websocket client
+const broadcastChannels = new Map<string, Set<WebSocket>>();
+
+function clientSubscribe(ws: WebSocket, broadcastChannel: string) {
+    ws.state.broadcastChannels.add(broadcastChannel);
+    if (!broadcastChannels.get(broadcastChannel)) {
+        broadcastChannels.set(broadcastChannel, new Set());
+    }
+
+    broadcastChannels.get(broadcastChannel)?.add(ws);
+}
+
+function clientUnsubscribe(ws: WebSocket, broadcastChannel: string) {
+    if (!ws.state) return;
+
+    ws.state.broadcastChannels.delete(broadcastChannel);
+
+    const set = broadcastChannels.get(broadcastChannel);
+    if (!set) return;
+
+    set.delete(ws);
+    if (set.size < 1) {
+        broadcastChannels.delete(broadcastChannel);
+    }
+}
+
+function clientUnsubscribeAll(ws: WebSocket) {
+    if (!ws.state) return;
+
+    ws.state.broadcastChannels.forEach(e => {
+        const set = broadcastChannels.get(e);
+        if (!set) return;
+
+        set.delete(ws);
+        if (set && set.size < 1) {
+            broadcastChannels.delete(e);
+        }
+    });
+
+    ws.state.broadcastChannels = new Set();
+}
+
+export function broadcast(channel: string, message: GatewayPayload) {
+    const members = broadcastChannels.get(channel);
+    if (!members) return;
+    
+    members.forEach(e => e.send(JSON.stringify(message)));
+}
+
 function closeWithError(ws: WebSocket, { code, message }: { code: number, message: string }) {
-    return ws.close(1000, `(${code}) ${message}`);
+    return ws.close(code, message);
 }
 
 function closeWithBadPayload(ws: WebSocket, hint: string) {
@@ -57,23 +107,33 @@ function sendPayload(ws: WebSocket, payload: GatewayPayload) {
 export default function(server: Server) {
     const wss = new WebSocketServer({ server });
 
-    setInterval(() => {
+    const batchInterval = setInterval(() => {
         wss.clients.forEach((e) => {
             const now = performance.now();
             if (e.state && (now - e.state.lastAliveCheck) >= GATEWAY_PING_INTERVAL) {
                 if (!e.state.ready) {
                     return closeWithError(e, gatewayErrors.AUTHENTICATION_TIMEOUT);
                 }
+                if (!e.state.alive) {
+                    return closeWithError(e, gatewayErrors.NO_PING);
+                }
             }
         });
     }, GATEWAY_BATCH_INTERVAL);
 
+    wss.on("close", () => {
+        console.warn("gateway: websocket server closed");
+        console.warn("gateway: clearing batch interval due to websocket server close");
+        clearInterval(batchInterval);
+    });
+
     wss.on("connection", (ws) => {
         ws.state = {
             user: undefined,
             alive: false,
             ready: false,
-            lastAliveCheck: performance.now()
+            lastAliveCheck: performance.now(),
+            broadcastChannels: new Set()
         };
 
         sendPayload(ws, {
@@ -83,6 +143,11 @@ export default function(server: Server) {
             }
         });
 
+        ws.on("close", () => {
+            clientUnsubscribeAll(ws);
+            console.log(broadcastChannels);
+        });
+
         ws.on("message", async (rawData, isBinary) => {
             if (isBinary) {
                 return closeWithBadPayload(ws, "Binary messages are not supported");
@@ -103,17 +168,30 @@ export default function(server: Server) {
                     if (!user) {
                         return closeWithError(ws, gatewayErrors.BAD_AUTH);
                     }
+                    // each user should have their own list of channels that they join
+                    const channels = await query("SELECT id, name, owner_id FROM channels");
+
+                    channels.rows.forEach(c => {
+                        clientSubscribe(ws, `channel:${c.id}`);
+                    });
+
                     ws.state.user = user;
                     ws.state.ready = true;
-                    
+
                     sendPayload(ws, {
                         t: GatewayPayloadType.Ready,
                         d: {
-                            user: ws.state.user,
+                            user: getPublicUserObject(ws.state.user),
+                            channels: channels.rows
                         }
                     })
                     break;
                 }
+                case GatewayPayloadType.Ping: {
+                    // TODO: also check session here and ensure packet is sent at the right time
+                    ws.state.alive = true;
+                    break;
+                }
                 default: {
                     return closeWithBadPayload(ws, "t: unknown type");
                 }
diff --git a/src/types/gatewayclientstate.d.ts b/src/types/gatewayclientstate.d.ts
index cf44b3a..72d10c8 100644
--- a/src/types/gatewayclientstate.d.ts
+++ b/src/types/gatewayclientstate.d.ts
@@ -3,4 +3,5 @@ interface GatewayClientState {
     ready: boolean,
     alive: boolean,
     lastAliveCheck: number,
+    broadcastChannels: Set<string>
 }