diff --git a/frontend/src/pages/AuthCallback.vue b/frontend/src/pages/AuthCallback.vue
new file mode 100644
index 0000000..4daae8d
--- /dev/null
+++ b/frontend/src/pages/AuthCallback.vue
@@ -0,0 +1,38 @@
+<template>
+  <q-page class="flex flex-center">
+    <q-spinner size="50px" />
+  </q-page>
+</template>
+
+<script setup>
+import { onMounted } from 'vue'
+import { useRoute, useRouter } from 'vue-router'
+import { useAuthStore } from '../stores/auth.js'
+import { exchangeGitlabCode } from '../services/gitlab.js'
+
+const route = useRoute()
+const router = useRouter()
+const auth = useAuthStore()
+
+onMounted(async () => {
+  if (route.path.includes('github')) {
+    const token = route.query.token
+    if (token) {
+      await auth.loginWithToken('github', token)
+      router.push('/repos')
+    } else {
+      router.push('/login?error=no_token')
+    }
+  } else if (route.path.includes('gitlab')) {
+    const code = route.query.code
+    if (code) {
+      const gitlabHost = sessionStorage.getItem('gitlab_host') || 'gitlab.com'
+      const { access_token } = await exchangeGitlabCode(code)
+      await auth.loginWithToken('gitlab', access_token, gitlabHost)
+      router.push('/repos')
+    } else {
+      router.push('/login?error=no_code')
+    }
+  }
+})
+</script>
diff --git a/frontend/src/pages/LoginPage.vue b/frontend/src/pages/LoginPage.vue
new file mode 100644
index 0000000..fd4ae6d
--- /dev/null
+++ b/frontend/src/pages/LoginPage.vue
@@ -0,0 +1,69 @@
+<template>
+  <q-page class="flex flex-center">
+    <q-card style="min-width: 360px">
+      <q-card-section>
+        <div class="text-h6">Sign in</div>
+      </q-card-section>
+
+      <q-card-section v-if="errorMessage">
+        <q-banner class="bg-negative text-white" rounded>
+          {{ errorMessage }}
+        </q-banner>
+      </q-card-section>
+
+      <q-card-section class="q-gutter-md">
+        <q-btn
+          color="dark"
+          icon="fab fa-github"
+          label="Login with GitHub"
+          class="full-width"
+          @click="loginGithub"
+        />
+      </q-card-section>
+
+      <q-separator />
+
+      <q-card-section class="q-gutter-md">
+        <q-input v-model="gitlabHost" label="GitLab host" outlined dense />
+        <q-btn
+          color="orange"
+          icon="fab fa-gitlab"
+          label="Login with GitLab"
+          class="full-width"
+          @click="loginGitlab"
+        />
+      </q-card-section>
+    </q-card>
+  </q-page>
+</template>
+
+<script setup>
+import { ref, computed } from 'vue'
+import { useRoute } from 'vue-router'
+import { startGitlabLogin } from '../services/gitlab.js'
+
+const route = useRoute()
+
+const gitlabHost = ref('gitlab.com')
+
+const errorMessage = computed(() => {
+  if (!route.query.error) return null
+  const messages = {
+    no_token: 'Authentication failed: no token received.',
+    no_code: 'Authentication failed: no code received.',
+  }
+  return messages[route.query.error] ?? `Authentication error: ${route.query.error}`
+})
+
+function loginGithub() {
+  const workerUrl = process.env.WORKER_URL
+  const clientId = process.env.GITHUB_CLIENT_ID
+  const redirectUri = `${workerUrl}/auth/github/callback`
+  const params = new URLSearchParams({ client_id: clientId, scope: 'repo user', redirect_uri: redirectUri })
+  window.location.href = `https://github.com/login/oauth/authorize?${params}`
+}
+
+async function loginGitlab() {
+  await startGitlabLogin(gitlabHost.value, process.env.GITLAB_CLIENT_ID)
+}
+</script>
diff --git a/frontend/src/router/routes.js b/frontend/src/router/routes.js
index 8050556..9b3b6db 100644
--- a/frontend/src/router/routes.js
+++ b/frontend/src/router/routes.js
@@ -2,7 +2,12 @@ const routes = [
   {
     path: '/',
     component: () => import('layouts/MainLayout.vue'),
-    children: [{ path: '', component: () => import('pages/IndexPage.vue') }],
+    children: [
+      { path: '', component: () => import('pages/IndexPage.vue') },
+      { path: '/login', component: () => import('pages/LoginPage.vue') },
+      { path: '/auth/github', component: () => import('pages/AuthCallback.vue') },
+      { path: '/auth/gitlab', component: () => import('pages/AuthCallback.vue') },
+    ],
   },
   {
     path: '/:catchAll(.*)*',
diff --git a/frontend/src/services/github.js b/frontend/src/services/github.js
new file mode 100644
index 0000000..ae66329
--- /dev/null
+++ b/frontend/src/services/github.js
@@ -0,0 +1,8 @@
+const BASE = 'https://api.github.com'
+
+export async function fetchCurrentUser(token) {
+  const res = await fetch(`${BASE}/user`, {
+    headers: { Authorization: `Bearer ${token}`, Accept: 'application/vnd.github+json' },
+  })
+  return res.json()
+}
diff --git a/frontend/src/stores/auth.js b/frontend/src/stores/auth.js
new file mode 100644
index 0000000..f7e234e
--- /dev/null
+++ b/frontend/src/stores/auth.js
@@ -0,0 +1,61 @@
+import { ref, computed } from 'vue'
+import { defineStore } from 'pinia'
+import { fetchCurrentUser } from '../services/github.js'
+
+const STORAGE_KEY = 'auth'
+
+export const useAuthStore = defineStore('auth', () => {
+  const provider = ref(null)
+  const token = ref(null)
+  const gitlabHost = ref(null)
+  const user = ref(null)
+
+  const isLoggedIn = computed(() => !!token.value)
+
+  // Hydrate from localStorage on store creation
+  const stored = localStorage.getItem(STORAGE_KEY)
+  if (stored) {
+    try {
+      const parsed = JSON.parse(stored)
+      provider.value = parsed.provider
+      token.value = parsed.token
+      gitlabHost.value = parsed.gitlabHost
+      user.value = parsed.user
+    } catch {
+      /* ignore */
+    }
+  }
+
+  async function loginWithToken(providerName, accessToken, host = 'gitlab.com') {
+    let fetchedUser = null
+
+    if (providerName === 'github') {
+      fetchedUser = await fetchCurrentUser(accessToken)
+    } else if (providerName === 'gitlab') {
+      const res = await fetch(`https://${host}/api/v4/user`, {
+        headers: { Authorization: `Bearer ${accessToken}` },
+      })
+      fetchedUser = await res.json()
+    }
+
+    provider.value = providerName
+    token.value = accessToken
+    gitlabHost.value = host
+    user.value = fetchedUser
+
+    localStorage.setItem(
+      STORAGE_KEY,
+      JSON.stringify({ provider: providerName, token: accessToken, gitlabHost: host, user: fetchedUser }),
+    )
+  }
+
+  function logout() {
+    provider.value = null
+    token.value = null
+    gitlabHost.value = null
+    user.value = null
+    localStorage.removeItem(STORAGE_KEY)
+  }
+
+  return { provider, token, gitlabHost, user, isLoggedIn, loginWithToken, logout }
+})