diff --git a/web-app/src/components/IdleTimeoutModal.vue b/web-app/src/components/IdleTimeoutModal.vue
new file mode 100644
index 0000000..e214421
--- /dev/null
+++ b/web-app/src/components/IdleTimeoutModal.vue
@@ -0,0 +1,53 @@
+<script setup lang="ts">
+import { useAuthStore } from '@/stores/auth-store'
+import { useTemplateRef, ref, computed } from 'vue'
+import ModalWrapper from './common/ModalWrapper.vue'
+import AppButton from './common/AppButton.vue'
+
+const timeoutModal = useTemplateRef("timeoutModal")
+const secondsUntilLogout = ref(30)
+const timeoutTimerId = ref<number | undefined>()
+const timePhrase = computed(() => {
+  if (secondsUntilLogout.value !== 1) {
+    return secondsUntilLogout.value + " seconds"
+  }
+  return secondsUntilLogout.value + " second"
+})
+
+const authStore = useAuthStore()
+
+function start() {
+  if (timeoutModal.value?.isOpen()) return
+  secondsUntilLogout.value = 30
+  timeoutModal.value?.show()
+  timeoutTimerId.value = window.setInterval(() => {
+    secondsUntilLogout.value = secondsUntilLogout.value - 1
+    if (secondsUntilLogout.value <= 0) {
+      authStore.onUserLoggedOut()
+      window.clearInterval(timeoutTimerId.value)
+    }
+  }, 1000)
+}
+
+function dismissTimeout() {
+  window.clearInterval(timeoutTimerId.value)
+  timeoutModal.value?.close()
+}
+
+defineExpose({ start })
+</script>
+<template>
+  <ModalWrapper ref="timeoutModal">
+    <template v-slot:default>
+      <p>
+        You've been inactive for a while, so to ensure the safety of your
+        personal information, you will be logged out in
+        <strong>{{ timePhrase }}</strong>
+        unless you click below to remain logged in.
+      </p>
+    </template>
+    <template v-slot:buttons>
+      <AppButton @click="dismissTimeout()">Stay Logged In</AppButton>
+    </template>
+  </ModalWrapper>
+</template>
diff --git a/web-app/src/components/common/ModalWrapper.vue b/web-app/src/components/common/ModalWrapper.vue
index 1829d1d..ffe87b4 100644
--- a/web-app/src/components/common/ModalWrapper.vue
+++ b/web-app/src/components/common/ModalWrapper.vue
@@ -23,24 +23,20 @@ function close(returnValue?: string) {
   dialog.value?.close(returnValue)
 }
 
-defineExpose({ show, close })
+function isOpen(): boolean {
+  return dialog.value?.open ?? false
+}
+
+defineExpose({ show, close, isOpen })
 </script>
 <template>
   <Teleport to="body">
-    <dialog
-      ref="dialog"
-      class="app-modal-dialog"
-      :id="id"
-    >
+    <dialog ref="dialog" class="app-modal-dialog" :id="id">
       <slot></slot>
 
       <div class="app-modal-dialog-actions">
         <slot name="buttons">
-          <AppButton
-            button-style="secondary"
-            @click="close()"
-            >Close</AppButton
-          >
+          <AppButton button-style="secondary" @click="close()">Close</AppButton>
         </slot>
       </div>
     </dialog>
diff --git a/web-app/src/pages/UserAccountLayout.vue b/web-app/src/pages/UserAccountLayout.vue
index 383f8a2..567e5be 100644
--- a/web-app/src/pages/UserAccountLayout.vue
+++ b/web-app/src/pages/UserAccountLayout.vue
@@ -7,14 +7,23 @@ pages.
 import { AuthApiClient } from '@/api/auth'
 import { getSelectedProfile } from '@/api/profile'
 import { secondsUntilExpired } from '@/api/token-util'
+import IdleTimeoutModal from '@/components/IdleTimeoutModal.vue'
 import { useAuthStore } from '@/stores/auth-store'
-import { onMounted, ref, type Ref } from 'vue'
+import { useIdleObserver } from '@idle-observer/vue3'
+import { onMounted, ref, useTemplateRef, type Ref } from 'vue'
 import { useRoute, useRouter } from 'vue-router'
 
 const route = useRoute()
 const router = useRouter()
 const authStore = useAuthStore()
 
+const IDLE_TIMEOUT_SECONDS = 300
+const idleTimeoutModal = useTemplateRef("idleTimeoutModal")
+useIdleObserver({
+  timeout: IDLE_TIMEOUT_SECONDS * 1000,
+  onIdle: () => idleTimeoutModal.value?.start()
+})
+
 const authCheckTimer: Ref<number | undefined> = ref(undefined)
 
 onMounted(async () => {
@@ -61,31 +70,24 @@ async function checkAuth() {
   <div>
     <header class="app-header-bar">
       <div>
-        <h1
-          class="app-header-text"
-          @click="onHeaderClicked()"
-        >
+        <h1 class="app-header-text" @click="onHeaderClicked()">
           Finnow
         </h1>
       </div>
       <div>
-        <span
-          class="app-user-widget"
-          @click="router.push('/me')"
-        >
+        <span class="app-user-widget" @click="router.push('/me')">
           <font-awesome-icon icon="fa-user"></font-awesome-icon>
         </span>
 
-        <span
-          class="app-logout-button"
-          @click="authStore.onUserLoggedOut()"
-        >
+        <span class="app-logout-button" @click="authStore.onUserLoggedOut()">
           <font-awesome-icon icon="fa-solid fa-arrow-right-from-bracket"></font-awesome-icon>
         </span>
       </div>
     </header>
 
     <RouterView></RouterView>
+
+    <IdleTimeoutModal ref="idleTimeoutModal" />
   </div>
 </template>