diff --git a/web/src/app/Connection.js b/web/src/app/Connection.js
index d22640a..ef8a627 100644
--- a/web/src/app/Connection.js
+++ b/web/src/app/Connection.js
@@ -3,7 +3,8 @@ import {basicAuth, encodeBase64Url, topicShortUrl, topicUrlWs} from "./utils";
 const retryBackoffSeconds = [5, 10, 15, 20, 30, 45];
 
 class Connection {
-    constructor(subscriptionId, baseUrl, topic, user, since, onNotification) {
+    constructor(connectionId, subscriptionId, baseUrl, topic, user, since, onNotification) {
+        this.connectionId = connectionId;
         this.subscriptionId = subscriptionId;
         this.baseUrl = baseUrl;
         this.topic = topic;
@@ -21,15 +22,15 @@ class Connection {
         // we don't want to re-trigger the main view re-render potentially hundreds of times.
 
         const wsUrl = this.wsUrl();
-        console.log(`[Connection, ${this.shortUrl}] Opening connection to ${wsUrl}`);
+        console.log(`[Connection, ${this.shortUrl}, ${this.connectionId}] Opening connection to ${wsUrl}`);
 
         this.ws = new WebSocket(wsUrl);
         this.ws.onopen = (event) => {
-            console.log(`[Connection, ${this.shortUrl}] Connection established`, event);
+            console.log(`[Connection, ${this.shortUrl}, ${this.connectionId}] Connection established`, event);
             this.retryCount = 0;
         }
         this.ws.onmessage = (event) => {
-            console.log(`[Connection, ${this.shortUrl}] Message received from server: ${event.data}`);
+            console.log(`[Connection, ${this.shortUrl}, ${this.connectionId}] Message received from server: ${event.data}`);
             try {
                 const data = JSON.parse(event.data);
                 if (data.event === 'open') {
@@ -41,33 +42,33 @@ class Connection {
                     'time' in data &&
                     'message' in data;
                 if (!relevantAndValid) {
-                    console.log(`[Connection, ${this.shortUrl}] Unexpected message. Ignoring.`);
+                    console.log(`[Connection, ${this.shortUrl}, ${this.connectionId}] Unexpected message. Ignoring.`);
                     return;
                 }
                 this.since = data.id;
                 this.onNotification(this.subscriptionId, data);
             } catch (e) {
-                console.log(`[Connection, ${this.shortUrl}] Error handling message: ${e}`);
+                console.log(`[Connection, ${this.shortUrl}, ${this.connectionId}] Error handling message: ${e}`);
             }
         };
         this.ws.onclose = (event) => {
             if (event.wasClean) {
-                console.log(`[Connection, ${this.shortUrl}] Connection closed cleanly, code=${event.code} reason=${event.reason}`);
+                console.log(`[Connection, ${this.shortUrl}, ${this.connectionId}] Connection closed cleanly, code=${event.code} reason=${event.reason}`);
                 this.ws = null;
             } else {
                 const retrySeconds = retryBackoffSeconds[Math.min(this.retryCount, retryBackoffSeconds.length-1)];
                 this.retryCount++;
-                console.log(`[Connection, ${this.shortUrl}] Connection died, retrying in ${retrySeconds} seconds`);
+                console.log(`[Connection, ${this.shortUrl}, ${this.connectionId}] Connection died, retrying in ${retrySeconds} seconds`);
                 this.retryTimeout = setTimeout(() => this.start(), retrySeconds * 1000);
             }
         };
         this.ws.onerror = (event) => {
-            console.log(`[Connection, ${this.shortUrl}] Error occurred: ${event}`, event);
+            console.log(`[Connection, ${this.shortUrl}, ${this.connectionId}] Error occurred: ${event}`, event);
         };
     }
 
     close() {
-        console.log(`[Connection, ${this.shortUrl}] Closing connection`);
+        console.log(`[Connection, ${this.shortUrl}, ${this.connectionId}] Closing connection`);
         const socket = this.ws;
         const retryTimeout = this.retryTimeout;
         if (socket !== null) {
diff --git a/web/src/app/ConnectionManager.js b/web/src/app/ConnectionManager.js
index 93f8659..42cd016 100644
--- a/web/src/app/ConnectionManager.js
+++ b/web/src/app/ConnectionManager.js
@@ -1,30 +1,39 @@
 import Connection from "./Connection";
+import {sha256} from "./utils";
 
 class ConnectionManager {
     constructor() {
-        this.connections = new Map();
+        this.connections = new Map(); // ConnectionId -> Connection (hash, see below)
     }
 
-    refresh(subscriptions, users, onNotification) {
+    async refresh(subscriptions, users, onNotification) {
         if (!subscriptions || !users) {
             return;
         }
         console.log(`[ConnectionManager] Refreshing connections`);
-        const subscriptionIds = subscriptions.map(s => s.id);
-        const deletedIds = Array.from(this.connections.keys()).filter(id => !subscriptionIds.includes(id));
+        const subscriptionsWithUsersAndConnectionId = await Promise.all(subscriptions
+            .map(async s => {
+                const [user] = users.filter(u => u.baseUrl === s.baseUrl);
+                const connectionId = await makeConnectionId(s, user);
+                return {...s, user, connectionId};
+            }));
+        const activeIds = subscriptionsWithUsersAndConnectionId.map(s => s.connectionId);
+        const deletedIds = Array.from(this.connections.keys()).filter(id => !activeIds.includes(id));
 
+        console.log(subscriptionsWithUsersAndConnectionId);
         // Create and add new connections
-        subscriptions.forEach(subscription => {
-            const id = subscription.id;
-            const added = !this.connections.get(id)
+        subscriptionsWithUsersAndConnectionId.forEach(subscription => {
+            const subscriptionId = subscription.id;
+            const connectionId = subscription.connectionId;
+            const added = !this.connections.get(connectionId)
             if (added) {
                 const baseUrl = subscription.baseUrl;
                 const topic = subscription.topic;
-                const [user] = users.filter(user => user.baseUrl === baseUrl);
+                const user = subscription.user;
                 const since = subscription.last;
-                const connection = new Connection(id, baseUrl, topic, user, since, onNotification);
-                this.connections.set(id, connection);
-                console.log(`[ConnectionManager] Starting new connection ${id}`);
+                const connection = new Connection(connectionId, subscriptionId, baseUrl, topic, user, since, onNotification);
+                this.connections.set(connectionId, connection);
+                console.log(`[ConnectionManager] Starting new connection ${connectionId} (subscription ${subscriptionId} with user ${user ? user.username : "anonymous"})`);
                 connection.start();
             }
         });
@@ -39,5 +48,12 @@ class ConnectionManager {
     }
 }
 
+const makeConnectionId = async (subscription, user) => {
+    const hash = (user)
+        ? await sha256(`${subscription.id}|${user.username}|${user.password}`)
+        : await sha256(`${subscription.id}`);
+    return hash.substring(0, 10);
+}
+
 const connectionManager = new ConnectionManager();
 export default connectionManager;
diff --git a/web/src/app/utils.js b/web/src/app/utils.js
index 1f458d8..19c5ae4 100644
--- a/web/src/app/utils.js
+++ b/web/src/app/utils.js
@@ -90,6 +90,12 @@ export const encodeBase64Url = (s) => {
         .replaceAll('=', '');
 }
 
+// https://jameshfisher.com/2017/10/30/web-cryptography-api-hello-world/
+export const sha256 = async (s) => {
+    const buf = await crypto.subtle.digest("SHA-256", new TextEncoder("utf-8").encode(s));
+    return Array.prototype.map.call(new Uint8Array(buf), x=>(('00'+x.toString(16)).slice(-2))).join('');
+}
+
 export const formatShortDateTime = (timestamp) => {
     return new Intl.DateTimeFormat('default', {dateStyle: 'short', timeStyle: 'short'})
         .format(new Date(timestamp * 1000));
diff --git a/web/src/components/App.js b/web/src/components/App.js
index 4d939b8..ada71cc 100644
--- a/web/src/components/App.js
+++ b/web/src/components/App.js
@@ -19,14 +19,11 @@ import pruner from "../app/Pruner";
 import subscriptionManager from "../app/SubscriptionManager";
 import userManager from "../app/UserManager";
 
-// TODO subscribe dialog:
-//  - check/use existing user
-//  - add baseUrl
-// TODO embed into ntfy server
+// TODO subscribe dialog check/use existing user
 // TODO make default server functional
-// TODO business logic with callbacks
+// TODO routing
+// TODO embed into ntfy server
 // TODO connection indicator in subscription list
-// TODO connectionmanager should react on users changes
 
 const App = () => {
     console.log(`[App] Rendering main view`);
@@ -53,9 +50,7 @@ const App = () => {
         setSelectedSubscription(newSelected);
     };
     const handleRequestPermission = () => {
-        notificationManager.maybeRequestPermission((granted) => {
-            setNotificationsGranted(granted);
-        })
+        notificationManager.maybeRequestPermission(granted => setNotificationsGranted(granted));
     };
     const handlePrefsClick = () => {
         setPrefsOpen(true);
@@ -91,7 +86,7 @@ const App = () => {
                 console.error(`[App] Error handling notification`, e);
             }
         };
-        connectionManager.refresh(subscriptions, users, handleNotification);
+        connectionManager.refresh(subscriptions, users, handleNotification); // Dangle
     }, [subscriptions, users]);
     useEffect(() => {
         const subscriptionId = (selectedSubscription) ? selectedSubscription.id : "";