diff --git a/src/routes/auth/register/+page.server.ts b/src/routes/auth/register/+page.server.ts
new file mode 100644
index 00000000..14b0e421
--- /dev/null
+++ b/src/routes/auth/register/+page.server.ts
@@ -0,0 +1,54 @@
+import type { Actions, PageServerLoad } from './$types'
+import { fail, redirect } from '@sveltejs/kit'
+
+export const load: PageServerLoad = async ({ locals, url }) => {
+	if (locals.session.isAuthenticated) {
+		redirect(302, url.searchParams.get('next') ?? '/me')
+	}
+	return {}
+}
+
+export const actions: Actions = {
+	default: async ({ request, fetch, url }) => {
+		const form = await request.formData()
+		const username = String(form.get('username') ?? '')
+		const email = String(form.get('email') ?? '')
+		const password = String(form.get('password') ?? '')
+		const password_confirmation = String(form.get('password_confirmation') ?? '')
+
+		// Basic validation
+		if (!username || !email || !password || !password_confirmation) {
+			return fail(400, {
+				error: 'All fields are required',
+				username,
+				email
+			})
+		}
+
+		if (password !== password_confirmation) {
+			return fail(400, {
+				error: "Passwords don't match",
+				username,
+				email
+			})
+		}
+
+		const res = await fetch('/auth/signup', {
+			method: 'POST',
+			headers: { 'Content-Type': 'application/json' },
+			body: JSON.stringify({ username, email, password, password_confirmation })
+		})
+
+		if (res.ok) {
+			redirect(303, url.searchParams.get('next') ?? '/me')
+		}
+
+		const j = await res.json().catch(() => ({}))
+		return fail(res.status, {
+			error: j.error ?? 'Registration failed',
+			details: j.details,
+			username,
+			email
+		})
+	}
+}
diff --git a/src/routes/auth/register/+page.svelte b/src/routes/auth/register/+page.svelte
new file mode 100644
index 00000000..59501224
--- /dev/null
+++ b/src/routes/auth/register/+page.svelte
@@ -0,0 +1,326 @@
+<script lang="ts">
+	import { enhance } from '$app/forms'
+	import AuthCard from '$lib/components/auth/AuthCard.svelte'
+	import Input from '$lib/components/ui/Input.svelte'
+	import Button from '$lib/components/ui/Button.svelte'
+	import { UserAdapter } from '$lib/api/adapters/user.adapter'
+	import * as m from '$lib/paraglide/messages'
+
+	interface Props {
+		form: {
+			error?: string
+			details?: { fieldErrors?: Record<string, string[]> }
+			username?: string
+			email?: string
+		} | null
+	}
+
+	let { form }: Props = $props()
+
+	let username = $state(form?.username ?? '')
+	let email = $state(form?.email ?? '')
+	let password = $state('')
+	let passwordConfirmation = $state('')
+	let isSubmitting = $state(false)
+
+	// Validation states
+	let usernameError = $state('')
+	let emailError = $state('')
+	let passwordError = $state('')
+	let passwordConfirmationError = $state('')
+
+	let isCheckingUsername = $state(false)
+	let isCheckingEmail = $state(false)
+	let usernameAvailable = $state<boolean | null>(null)
+	let emailAvailable = $state<boolean | null>(null)
+
+	// Debounce timers
+	let usernameTimer: ReturnType<typeof setTimeout>
+	let emailTimer: ReturnType<typeof setTimeout>
+
+	const userAdapter = new UserAdapter()
+
+	// Username validation regex
+	const usernameRegex = /^[a-zA-Z0-9_-]+$/
+	const emailRegex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/
+
+	// Computed validation
+	const isFormValid = $derived(
+		username.length >= 3 &&
+			username.length <= 20 &&
+			usernameRegex.test(username) &&
+			usernameAvailable === true &&
+			emailRegex.test(email) &&
+			emailAvailable === true &&
+			password.length >= 8 &&
+			passwordConfirmation === password &&
+			!usernameError &&
+			!emailError &&
+			!passwordError &&
+			!passwordConfirmationError
+	)
+
+	function validateUsername(value: string) {
+		if (value.length === 0) {
+			usernameError = ''
+			usernameAvailable = null
+			return
+		}
+		if (value.length < 3) {
+			usernameError = m.auth_register_errors_usernameMin()
+			usernameAvailable = null
+			return
+		}
+		if (value.length > 20) {
+			usernameError = m.auth_register_errors_usernameMax()
+			usernameAvailable = null
+			return
+		}
+		if (!usernameRegex.test(value)) {
+			usernameError = m.auth_register_errors_usernameFormat()
+			usernameAvailable = null
+			return
+		}
+		usernameError = ''
+	}
+
+	function validateEmail(value: string) {
+		if (value.length === 0) {
+			emailError = ''
+			emailAvailable = null
+			return
+		}
+		if (!emailRegex.test(value)) {
+			emailError = m.auth_register_errors_emailInvalid()
+			emailAvailable = null
+			return
+		}
+		emailError = ''
+	}
+
+	function validatePassword(value: string) {
+		if (value.length === 0) {
+			passwordError = ''
+			return
+		}
+		if (value.length < 8) {
+			passwordError = m.auth_register_errors_passwordMin()
+			return
+		}
+		passwordError = ''
+	}
+
+	function validatePasswordConfirmation(value: string, original: string) {
+		if (value.length === 0) {
+			passwordConfirmationError = ''
+			return
+		}
+		if (value !== original) {
+			passwordConfirmationError = m.auth_register_errors_passwordMismatch()
+			return
+		}
+		passwordConfirmationError = ''
+	}
+
+	async function checkUsernameAvailability(value: string) {
+		if (value.length < 3 || !usernameRegex.test(value)) return
+
+		isCheckingUsername = true
+		try {
+			const result = await userAdapter.checkUsernameAvailability(value)
+			// Only update if the value hasn't changed
+			if (username === value) {
+				usernameAvailable = result.available
+				if (!result.available) {
+					usernameError = m.auth_register_errors_usernameTaken()
+				}
+			}
+		} catch {
+			// Silently fail availability check
+		} finally {
+			isCheckingUsername = false
+		}
+	}
+
+	async function checkEmailAvailability(value: string) {
+		if (!emailRegex.test(value)) return
+
+		isCheckingEmail = true
+		try {
+			const result = await userAdapter.checkEmailAvailability(value)
+			// Only update if the value hasn't changed
+			if (email === value) {
+				emailAvailable = result.available
+				if (!result.available) {
+					emailError = m.auth_register_errors_emailTaken()
+				}
+			}
+		} catch {
+			// Silently fail availability check
+		} finally {
+			isCheckingEmail = false
+		}
+	}
+
+	function onUsernameInput(e: Event) {
+		const target = e.target as HTMLInputElement
+		username = target.value
+		usernameAvailable = null
+
+		clearTimeout(usernameTimer)
+		validateUsername(username)
+
+		if (username.length >= 3 && !usernameError) {
+			usernameTimer = setTimeout(() => checkUsernameAvailability(username), 300)
+		}
+	}
+
+	function onEmailInput(e: Event) {
+		const target = e.target as HTMLInputElement
+		email = target.value
+		emailAvailable = null
+
+		clearTimeout(emailTimer)
+		validateEmail(email)
+
+		if (emailRegex.test(email) && !emailError) {
+			emailTimer = setTimeout(() => checkEmailAvailability(email), 300)
+		}
+	}
+
+	function onPasswordInput(e: Event) {
+		const target = e.target as HTMLInputElement
+		password = target.value
+		validatePassword(password)
+		// Re-validate confirmation if it has content
+		if (passwordConfirmation.length > 0) {
+			validatePasswordConfirmation(passwordConfirmation, password)
+		}
+	}
+
+	function onPasswordConfirmationInput(e: Event) {
+		const target = e.target as HTMLInputElement
+		passwordConfirmation = target.value
+		validatePasswordConfirmation(passwordConfirmation, password)
+	}
+
+	// Derive validation icon states
+	const usernameIcon = $derived(
+		isCheckingUsername ? 'loader' : usernameAvailable === true ? 'check' : usernameAvailable === false ? 'x' : undefined
+	)
+
+	const emailIcon = $derived(
+		isCheckingEmail ? 'loader' : emailAvailable === true ? 'check' : emailAvailable === false ? 'x' : undefined
+	)
+</script>
+
+<svelte:head>
+	<title>{m.auth_register_title()} | Granblue Party</title>
+</svelte:head>
+
+<AuthCard title={m.auth_register_title()}>
+	<form
+		method="post"
+		use:enhance={() => {
+			isSubmitting = true
+			return async ({ update }) => {
+				isSubmitting = false
+				await update()
+			}
+		}}
+	>
+		<Input
+			type="text"
+			name="username"
+			label={m.auth_register_username()}
+			value={username}
+			oninput={onUsernameInput}
+			autocomplete="username"
+			minlength={3}
+			maxLength={20}
+			required
+			fullWidth
+			contained
+			error={usernameError}
+			rightIcon={usernameIcon}
+		/>
+
+		<Input
+			type="email"
+			name="email"
+			label={m.auth_register_email()}
+			value={email}
+			oninput={onEmailInput}
+			autocomplete="email"
+			required
+			fullWidth
+			contained
+			error={emailError}
+			rightIcon={emailIcon}
+		/>
+
+		<Input
+			type="password"
+			name="password"
+			label={m.auth_register_password()}
+			value={password}
+			oninput={onPasswordInput}
+			autocomplete="new-password"
+			minlength={8}
+			required
+			fullWidth
+			contained
+			error={passwordError}
+		/>
+
+		<Input
+			type="password"
+			name="password_confirmation"
+			label={m.auth_register_confirmPassword()}
+			value={passwordConfirmation}
+			oninput={onPasswordConfirmationInput}
+			autocomplete="new-password"
+			required
+			fullWidth
+			contained
+			error={passwordConfirmationError}
+		/>
+
+		{#if form?.error}
+			<p class="error">{form.error}</p>
+		{/if}
+
+		<Button type="submit" variant="primary" fullWidth disabled={isSubmitting || !isFormValid}>
+			{isSubmitting ? m.auth_register_submitting() : m.auth_register_submit()}
+		</Button>
+	</form>
+
+	{#snippet footer()}
+		<p>
+			{m.auth_register_hasAccount()}
+			<a href="/auth/login">{m.auth_register_login()}</a>
+		</p>
+	{/snippet}
+</AuthCard>
+
+<style lang="scss">
+	@use '$src/themes/spacing' as *;
+	@use '$src/themes/colors' as *;
+	@use '$src/themes/typography' as *;
+
+	form {
+		display: flex;
+		flex-direction: column;
+		gap: $unit-2x;
+	}
+
+	.error {
+		color: $error;
+		font-size: $font-small;
+		text-align: center;
+		margin: 0;
+		padding: $unit $unit-2x;
+		background: var(--danger-bg);
+		border-radius: $unit;
+	}
+</style>