diff --git a/frontend/src/routes/[famSlug]/join/[username]/+page.server.ts b/frontend/src/routes/[famSlug]/join/[username]/+page.server.ts
new file mode 100644
index 0000000..f05325e
--- /dev/null
+++ b/frontend/src/routes/[famSlug]/join/[username]/+page.server.ts
@@ -0,0 +1,24 @@
+import { fail, redirect } from '@sveltejs/kit';
+import { redeemOtp } from '$lib/server/member-otp';
+import { setSessionCookie } from '$lib/server/session';
+
+export const actions = {
+	default: async (event) => {
+		const famSlug = event.params.famSlug;
+		const username = event.params.username;
+		const fd = await event.request.formData();
+		const otp = (fd.get('otp') || '').toString().trim();
+
+		if (!otp) return fail(400, { error: 'Enter the code shown by your parent.' });
+
+		try {
+			const token = await redeemOtp({ famSlug, username, otp });
+			event.cookies.delete('device_token', { path: '/' });
+			setSessionCookie(event.cookies, token);
+		} catch (e) {
+			return fail(400, { error: e instanceof Error ? e.message : 'Join failed' });
+		}
+
+		throw redirect(303, `/${famSlug}/${encodeURIComponent(username)}`);
+	}
+};
\ No newline at end of file
diff --git a/frontend/src/routes/[famSlug]/join/[username]/+page.svelte b/frontend/src/routes/[famSlug]/join/[username]/+page.svelte
new file mode 100644
index 0000000..27dc511
--- /dev/null
+++ b/frontend/src/routes/[famSlug]/join/[username]/+page.svelte
@@ -0,0 +1,46 @@
+<script lang="ts">
+	import { page } from '$app/state';
+	import { enhance } from '$app/forms';
+	import { Button } from '$lib/components';
+
+	const famSlug = page.params.famSlug;
+	const username = page.params.username;
+	let otp = $state(page.url.searchParams.get('code') || '');
+	let { form } = $props();
+</script>
+
+<svelte:head><title>Join {famSlug}</title></svelte:head>
+
+<main class="mx-auto flex min-h-screen max-w-md flex-col items-center justify-center px-6">
+	<section class="w-full rounded-2xl border border-slate-200 bg-white p-8 text-center shadow-sm">
+		<div class="mx-auto mb-4 flex h-12 w-12 items-center justify-center rounded-full bg-indigo-100 text-2xl">
+			🏠
+		</div>
+		<h1 class="text-xl font-bold text-slate-900">Welcome to {famSlug}!</h1>
+		<p class="mt-1 text-sm text-slate-500">
+			Hi <span class="font-semibold text-slate-700">{username}</span> — enter the code your parent
+			gave you to get started.
+		</p>
+
+		<form class="mt-6 flex flex-col gap-3" method="POST" use:enhance={() => ({})}>
+			<input
+				type="text"
+				name="otp"
+				bind:value={otp}
+				inputmode="numeric"
+				maxlength="6"
+				placeholder="6-digit code"
+				autocomplete="one-time-code"
+				class="w-full rounded-lg border border-slate-300 px-4 py-3 text-center text-2xl tracking-[0.5em] text-slate-900 outline-none focus:border-indigo-500 focus:ring-2 focus:ring-indigo-200"
+			/>
+			{#if form?.error}
+				<p class="text-sm font-medium text-rose-600">{form.error}</p>
+			{/if}
+			<Button type="submit" variant="primary" size="lg">Join</Button>
+		</form>
+
+		<p class="mt-6 text-xs text-slate-400">
+			Code is valid for 20 minutes. Ask your parent for a new one if it expires.
+		</p>
+	</section>
+</main>
\ No newline at end of file