diff --git a/common/user.ts b/common/user.ts
index 477139fd..2960bda0 100644
--- a/common/user.ts
+++ b/common/user.ts
@@ -38,6 +38,7 @@ export type User = {
 
   referredByUserId?: string
   referredByContractId?: string
+  lastPingTime?: number
 }
 
 export const STARTING_BALANCE = ENV_CONFIG.startingBalance ?? 1000
@@ -57,7 +58,6 @@ export type PrivateUser = {
   initialIpAddress?: string
   apiKey?: string
   notificationPreferences?: notification_subscribe_types
-  lastTimeCheckedBonuses?: number
 }
 
 export type notification_subscribe_types = 'all' | 'less' | 'none'
diff --git a/firestore.rules b/firestore.rules
index 918448d6..196c5992 100644
--- a/firestore.rules
+++ b/firestore.rules
@@ -20,16 +20,17 @@ service cloud.firestore {
       allow read;
       allow update: if resource.data.id == request.auth.uid
                        && request.resource.data.diff(resource.data).affectedKeys()
-                                                                    .hasOnly(['bio', 'bannerUrl', 'website', 'twitterHandle', 'discordHandle', 'followedCategories', 'referredByContractId']);
-          allow update: if resource.data.id == request.auth.uid
-                             && request.resource.data.diff(resource.data).affectedKeys()
-                              .hasOnly(['referredByUserId'])
-                              // only one referral allowed per user
-                              && !("referredByUserId" in resource.data)
-                              // user can't refer themselves
-                              && !(resource.data.id == request.resource.data.referredByUserId);
-                              // quid pro quos enabled (only once though so nbd) - bc I can't make this work:
-                              // && (get(/databases/$(database)/documents/users/$(request.resource.data.referredByUserId)).referredByUserId == resource.data.id);
+                                                                    .hasOnly(['bio', 'bannerUrl', 'website', 'twitterHandle', 'discordHandle', 'followedCategories', 'referredByContractId', 'lastPingTime']);
+      // User referral rules
+      allow update: if resource.data.id == request.auth.uid
+                         && request.resource.data.diff(resource.data).affectedKeys()
+                          .hasOnly(['referredByUserId'])
+                          // only one referral allowed per user
+                          && !("referredByUserId" in resource.data)
+                          // user can't refer themselves
+                          && !(resource.data.id == request.resource.data.referredByUserId);
+                          // quid pro quos enabled (only once though so nbd) - bc I can't make this work:
+                          // && (get(/databases/$(database)/documents/users/$(request.resource.data.referredByUserId)).referredByUserId == resource.data.id);
     }
 
   	match /{somePath=**}/portfolioHistory/{portfolioHistoryId} {
diff --git a/web/components/follow-list.tsx b/web/components/follow-list.tsx
index c935f73d..391ce4d3 100644
--- a/web/components/follow-list.tsx
+++ b/web/components/follow-list.tsx
@@ -7,6 +7,7 @@ import { FollowButton } from './follow-button'
 import { Col } from './layout/col'
 import { Row } from './layout/row'
 import { UserLink } from './user-page'
+import { OnlineUserAvatar } from 'web/components/online-user-list'
 
 export function FollowList(props: { userIds: string[] }) {
   const { userIds } = props
@@ -63,10 +64,7 @@ function UserFollowItem(props: {
 
   return (
     <Row className={clsx('items-center justify-between gap-2 p-2', className)}>
-      <Row className="items-center gap-2">
-        <Avatar username={user?.username} avatarUrl={user?.avatarUrl} />
-        {user && <UserLink name={user.name} username={user.username} />}
-      </Row>
+      <OnlineUserAvatar user={user} />
       {!hideFollowButton && (
         <FollowButton
           isFollowing={isFollowing}
diff --git a/web/components/nav/sidebar.tsx b/web/components/nav/sidebar.tsx
index baa60719..c2a7bcde 100644
--- a/web/components/nav/sidebar.tsx
+++ b/web/components/nav/sidebar.tsx
@@ -13,7 +13,7 @@ import clsx from 'clsx'
 import Link from 'next/link'
 import { useRouter } from 'next/router'
 import { usePrivateUser, useUser } from 'web/hooks/use-user'
-import { firebaseLogout, User } from 'web/lib/firebase/users'
+import { firebaseLogout, updateUser, User } from 'web/lib/firebase/users'
 import { ManifoldLogo } from './manifold-logo'
 import { MenuButton } from './menu'
 import { ProfileSummary } from './profile-menu'
@@ -208,6 +208,17 @@ export default function Sidebar(props: { className?: string }) {
     href: `${groupPath(group.slug)}/${GROUP_CHAT_SLUG}`,
   }))
 
+  useEffect(() => {
+    if (!user) return
+    // set ping time to now every 60 seconds to indicate that the user is active
+    const pingInterval = setInterval(() => {
+      updateUser(user.id, {
+        lastPingTime: Date.now(),
+      })
+    }, 1000 * 30)
+    return () => clearInterval(pingInterval)
+  }, [user])
+
   return (
     <nav aria-label="Sidebar" className={className}>
       <ManifoldLogo className="py-6" twoLine />
diff --git a/web/components/online-user-list.tsx b/web/components/online-user-list.tsx
new file mode 100644
index 00000000..7156ad91
--- /dev/null
+++ b/web/components/online-user-list.tsx
@@ -0,0 +1,56 @@
+import clsx from 'clsx'
+import { Avatar } from './avatar'
+import { Col } from './layout/col'
+import { Row } from './layout/row'
+import { UserLink } from './user-page'
+import { User } from 'common/user'
+import { UserCircleIcon } from '@heroicons/react/solid'
+import { useUsers } from 'web/hooks/use-users'
+import { partition } from 'lodash'
+
+const isOnline = (user?: User) =>
+  user && user.lastPingTime && user.lastPingTime > Date.now() - 5 * 60 * 1000
+
+export function OnlineUserList(props: { users: User[] }) {
+  let { users } = props
+  const liveUsers = useUsers().filter((user) =>
+    users.map((u) => u.id).includes(user.id)
+  )
+  if (liveUsers) users = liveUsers
+  const [onlineUsers, offlineUsers] = partition(users, (user) => isOnline(user))
+  return (
+    <Col className="mt-4 gap-1">
+      {onlineUsers
+        .concat(offlineUsers)
+        .slice(0, 15)
+        .map((user) => (
+          <Row
+            key={user.id}
+            className={clsx('items-center justify-between gap-2 p-2')}
+          >
+            <OnlineUserAvatar key={user.id} user={user} />
+          </Row>
+        ))}
+    </Col>
+  )
+}
+
+export function OnlineUserAvatar(props: { user?: User; className?: string }) {
+  const { user, className } = props
+
+  return (
+    <Row className={clsx('relative items-center gap-2', className)}>
+      <Avatar
+        username={user?.username}
+        avatarUrl={user?.avatarUrl}
+        className={className}
+      />
+      {user && <UserLink name={user.name} username={user.username} />}
+      {isOnline(user) && (
+        <div className="absolute left-0 top-0 ">
+          <UserCircleIcon className="text-primary bg-primary h-3 w-3 rounded-full border-2 border-white" />
+        </div>
+      )}
+    </Row>
+  )
+}
diff --git a/web/pages/group/[...slugs]/index.tsx b/web/pages/group/[...slugs]/index.tsx
index 3fa64964..9620894f 100644
--- a/web/pages/group/[...slugs]/index.tsx
+++ b/web/pages/group/[...slugs]/index.tsx
@@ -55,6 +55,7 @@ import { FollowList } from 'web/components/follow-list'
 import { SearchIcon } from '@heroicons/react/outline'
 import { useTipTxns } from 'web/hooks/use-tip-txns'
 import { JoinOrLeaveGroupButton } from 'web/components/groups/groups-button'
+import { OnlineUserList } from 'web/components/online-user-list'
 
 export const getStaticProps = fromPropz(getStaticPropz)
 export async function getStaticPropz(props: { params: { slugs: string[] } }) {
@@ -174,7 +175,12 @@ export default function GroupPage(props: {
 
   const rightSidebar = (
     <Col className="mt-6 hidden xl:block">
-      <JoinOrCreateButton group={group} user={user} isMember={!!isMember} />
+      <JoinOrAddQuestionsButtons
+        group={group}
+        user={user}
+        isMember={!!isMember}
+      />
+      <OnlineUserList users={members} />
     </Col>
   )
   const leaderboard = (
@@ -254,7 +260,6 @@ export default function GroupPage(props: {
         description={`Created by ${creator.name}. ${group.about}`}
         url={groupPath(group.slug)}
       />
-
       <Col className="px-3">
         <Row className={'items-center justify-between gap-4'}>
           <div className={'sm:mb-1'}>
@@ -270,7 +275,7 @@ export default function GroupPage(props: {
             </div>
           </div>
           <div className="hidden sm:block xl:hidden">
-            <JoinOrCreateButton
+            <JoinOrAddQuestionsButtons
               group={group}
               user={user}
               isMember={!!isMember}
@@ -278,10 +283,13 @@ export default function GroupPage(props: {
           </div>
         </Row>
         <div className="block sm:hidden">
-          <JoinOrCreateButton group={group} user={user} isMember={!!isMember} />
+          <JoinOrAddQuestionsButtons
+            group={group}
+            user={user}
+            isMember={!!isMember}
+          />
         </div>
       </Col>
-
       <Tabs
         currentPageForAnalytics={groupPath(group.slug)}
         className={'mb-0 sm:mb-2'}
@@ -292,7 +300,7 @@ export default function GroupPage(props: {
   )
 }
 
-function JoinOrCreateButton(props: {
+function JoinOrAddQuestionsButtons(props: {
   group: Group
   user: User | null | undefined
   isMember: boolean