Best for
Developers who want a complete Supabase auth setup — login, signup, protected routes, session handling — without writing the boilerplate from scratch
Stack
A ready-made Supabase Auth Starter UI you can fork, run, and customize with the prompt pack below.
What's actually inside
The honest engineer's breakdown — what the Supabase Auth Startertemplate does, how it's wired, and where it's opinionated.
The Supabase Auth Starter is the most complete auth template in the v0 community for Supabase users. It ships six interconnected pieces: a /login page with email + password form wired to supabase.auth.signInWithPassword, a /signup page with email, password, and confirm-password fields wired to supabase.auth.signUp, an Auth Callback Route at app/auth/callback/route.ts that exchanges the OAuth code for a session, middleware.ts using createServerClient to check session and redirect unauthenticated requests to /login, a Protected Dashboard at /dashboard that only renders when supabase.auth.getUser() returns a valid user, and a User Button in the header showing the user's email and a sign-out option.
The stack leans on the @supabase/ssr package for the critical server/client split. createServerClient goes in middleware and Server Components; createBrowserClient goes in client components that need to call Supabase from the browser. This separation is correct and idiomatic — it avoids the common mistake of using the anon client everywhere and breaking cookie-based session persistence.
The honest caveats: email confirmation is enabled by default in Supabase, which means test sign-ups will require clicking a link in an email — this trips up developers the first time. The free Supabase tier also rate-limits confirmation emails to 4/hour, which makes rapid testing painful. The prompt pack covers both disabling confirmation for development and configuring custom SMTP for production. Do not use the deprecated @supabase/auth-helpers-nextjs package that older tutorials reference — this template already uses the correct @supabase/ssr path.
Key UI components
Login Page/login route with email + password form wired to supabase.auth.signInWithPassword
Signup Page/signup route with email, password, confirm-password fields wired to supabase.auth.signUp
Auth Callback Routeapp/auth/callback/route.ts that exchanges OAuth code for a Supabase session and sets cookies
Middlewaremiddleware.ts using createServerClient to check session and redirect to /login on protected routes
Protected Dashboard/dashboard page that only renders when supabase.auth.getUser() returns a valid user
User ButtonHeader component showing signed-in user's email and a sign-out button
Libraries it leans on
@supabase/supabase-jsCore auth calls: signInWithPassword, signUp, signOut, getUser
@supabase/ssrcreateServerClient and createBrowserClient factory for correct server/client auth separation
shadcn/uiForm, Input, Button, Card, and Alert components across all auth pages
Fork it and get it running
This template has more moving parts than a simple login screen — you need a Supabase project and a few environment variables before the auth flow works end-to-end. Follow these steps in order and you will have a working signup → confirmation → login → dashboard flow.
Fork the template in V0
Open https://v0.dev/chat/community/VLaYTHTngZT in your browser. Click the "Fork" button in the top-right corner. You will land in a new V0 project with the full auth stack — Login Page, Signup Page, middleware, callback route, and Protected Dashboard — already in place and a live preview showing the login form.
Tip: Sign in to v0.dev before clicking Fork to avoid being redirected mid-flow.
You should see: A new V0 project opens with the login form visible in the preview panel and all auth files present in the project.
Create a Supabase project and copy your keys
Go to supabase.com and create a new project (the free tier works). Once the project finishes initializing, go to Project Settings → API. Copy your Project URL and the anon public key. These are the two values you need — the URL usually looks like https://abcdefghij.supabase.co and the anon key starts with 'eyJ'.
Tip: Never copy the service_role key into the Vars panel for client-side use — it bypasses RLS and should only be used in server-only code.
You should see: You have the Supabase Project URL and anon key ready to paste.
Add environment variables in the Vars panel
Click the Vars panel icon in V0. Add three variables: NEXT_PUBLIC_SUPABASE_URL (your Supabase project URL), NEXT_PUBLIC_SUPABASE_ANON_KEY (the anon/public key from Step 2), and NEXT_PUBLIC_SITE_URL (your Vercel production domain — e.g. https://yourapp.com). The NEXT_PUBLIC_ prefix is required on the first two so they are available to the browser-side Supabase client.
Tip: Set NEXT_PUBLIC_SITE_URL to your production Vercel URL even before you have a custom domain — you can use the Vercel subdomain for now.
You should see: Three environment variables are saved in the Vars panel and will be injected into the build.
Configure Redirect URLs in Supabase Dashboard
In your Supabase Dashboard, go to Authentication → URL Configuration. Under "Redirect URLs", add your Vercel production domain followed by /auth/callback — for example https://yourapp.com/auth/callback. This tells Supabase which URLs are allowed as OAuth and magic link redirect targets. Without this step, any OAuth or email confirmation redirect will be blocked by Supabase.
Tip: You can also add a wildcard for Vercel preview URLs: https://*.vercel.app/auth/callback — useful for testing feature branches.
You should see: Supabase's URL Configuration shows your production domain in the Redirect URLs list.
Deploy to Vercel
Click Share → Publish → "Publish to Production" in V0. The build completes in under 60 seconds and your app goes live on a Vercel subdomain. You can now test the full sign-up → email confirmation → login → dashboard flow on the live URL. If confirmation emails are not arriving, see the troubleshooting note about Supabase's 4 emails/hour rate limit on the free tier.
Tip: Test with a real email address you can access — Supabase's confirmation email goes to the address used in sign-up.
You should see: The live Vercel URL shows the Login Page; signing up delivers a confirmation email; clicking the link lands on the Protected Dashboard.
Brand the auth pages in Design Mode
Press Option+D in V0 to open Design Mode. Update the Login Page and Signup Page headlines to your product name. Add your logo to the header component. Adjust brand colors on the Button and Card components. All Design Mode changes are free and do not spend credits. When done, click Share → Publish → "Publish to Production" again to push the visual updates live.
You should see: The live auth pages show your brand logo, product name, and color palette.
The prompt pack
Copy-paste these straight into v0's chat to customize the Supabase Auth Startertemplate. Each one names this template's own components — no generic filler.
Add email confirmation flow messaging
Makes the sign-up flow feel complete by giving users clear feedback at each step — form submitted, check email, confirmed, redirected.
Update the Signup Page submit handler to show a 'Check your email to confirm your account' success message after supabase.auth.signUp returns — replace the form with this message so the user knows what to do next. Add an /auth/confirm page that handles the email confirmation token from Supabase's magic link using the existing Auth Callback Route pattern. Show a 'Email confirmed! Redirecting to dashboard...' message before navigating to /dashboard.
Add Google OAuth to the Login Page
Adds one-click Google sign-in to the Login Page by reusing the Auth Callback Route already in the template.
Add a shadcn/ui Button variant='outline' with a Google SVG icon to the Login Page above the email form, separated by a horizontal 'or continue with email' divider. Wire it to supabase.auth.signInWithOAuth({ provider: 'google', options: { redirectTo: process.env.NEXT_PUBLIC_SITE_URL + '/auth/callback' } }). The existing Auth Callback Route at app/auth/callback/route.ts already handles the code exchange, so no new route is needed — just the button wiring on the Login Page.Add user profiles table with Row Level Security
Creates a profiles table with RLS so each user sees only their own data, and auto-populates it on first login via the Auth Callback Route.
In the Supabase SQL editor, run: CREATE TABLE profiles (id UUID REFERENCES auth.users PRIMARY KEY, display_name TEXT, avatar_url TEXT, created_at TIMESTAMPTZ DEFAULT NOW()); ALTER TABLE profiles ENABLE ROW LEVEL SECURITY; CREATE POLICY 'users see own profile' ON profiles FOR ALL USING (auth.uid() = id). Then add a profile creation step in the Auth Callback Route using the Supabase admin client (SUPABASE_SERVICE_ROLE_KEY — server-only, no NEXT_PUBLIC_ prefix): check if a profile exists for the user id; if not, insert display_name and avatar_url from user.user_metadata.
Add password reset flow
Adds a complete password reset flow — request email, click link, set new password — using the Auth Callback Route already in the template to handle the redirect.
Add a 'Forgot password?' link on the Login Page below the Submit Button, linking to /reset-password. Create /reset-password with an email input form that calls supabase.auth.resetPasswordForEmail(email, { redirectTo: process.env.NEXT_PUBLIC_SITE_URL + '/auth/callback?next=/update-password' }) and shows a 'Check your email for a reset link' message on success. Create /update-password with a new password input form that calls supabase.auth.updateUser({ password: newPassword }) — this route should only be accessible after the email link confirms the session in the Auth Callback Route.Add role-based access control for admin routes
Extends the existing middleware with role checks so admin routes are protected at the server level — unauthenticated and unauthorized users both get redirected.
Add a role column to the profiles table: ALTER TABLE profiles ADD COLUMN role TEXT DEFAULT 'user'. Create an admin-only route /admin. Update middleware.ts to check the role after verifying the Supabase session: fetch supabase.from('profiles').select('role').eq('id', user.id).single() using a server Supabase client; if the user is accessing any /admin path and role !== 'admin', redirect to /dashboard?error=insufficient_permissions. Add a shadcn/ui Alert on the Protected Dashboard that reads the error query param and displays an access restriction message. Add SUPABASE_SERVICE_ROLE_KEY (no NEXT_PUBLIC_ prefix) to Vars for admin operations that bypass RLS.Add realtime user presence to the Protected Dashboard
Shows a live count of authenticated users currently viewing the Protected Dashboard using Supabase Realtime presence — no additional backend required.
In the Protected Dashboard component, add a Supabase Realtime presence channel after the user session is confirmed: supabase.channel('online-users').on('presence', { event: 'sync' }, () => { const state = channel.presenceState(); setOnlineUsers(Object.keys(state).length) }).subscribe(async (status) => { if (status === 'SUBSCRIBED') await channel.track({ user_id: user.id, online_at: new Date().toISOString() }) }). Add a cleanup that calls channel.unsubscribe() in the useEffect return. Show the online user count as a shadcn/ui Badge in the Protected Dashboard header next to the User Button.Gotchas when you extend it
The failures people actually hit when they push this template past its defaults — and the exact fix for each.
`Import Error | Failed to load "@supabase/ssr" from "blob..."` in V0 previewWhy: @supabase/ssr fails through V0's esm.sh preview sandbox module resolution. The package uses server-specific Node.js APIs (cookie handling, headers) that cannot be bundled in the browser-based preview environment.
Fix: The error only occurs in the V0 preview sandbox — the app works correctly after deployment to Vercel. Click Share → Publish to Production and test the Supabase auth flow on the live Vercel URL.
Dismiss the @supabase/ssr preview import error; this is a V0 sandbox limitation. Click Share → Publish to Production and test the Supabase auth flow on the live Vercel URL
Middleware redirects every request to /login in an infinite loopWhy: If the middleware's createServerClient is not correctly configured with cookie read and write handlers, every request is treated as unauthenticated — including the /login page itself — causing a redirect loop.
Fix: Verify that middleware.ts uses the exact createServerClient pattern from @supabase/ssr with both getAll and setAll cookie methods wired to the request and response objects.
Check that middleware.ts uses createServerClient from @supabase/ssr with cookieOptions: { getAll: () => request.cookies.getAll(), setAll: (cookies) => cookies.forEach(c => response.cookies.set(c)) }Sign-up confirmation emails not received — stuck at 0/4 per hour limitWhy: Supabase free tier has a 4 emails/hour rate limit per project. If you have tested sign-up multiple times in development, the confirmation email delivery may be exhausted. Emails also frequently land in spam.
Fix: For development: in Supabase Dashboard → Authentication → Providers → Email, disable 'Confirm email'. For production: configure a custom SMTP provider (Resend or Postmark) in Supabase Dashboard → Auth → SMTP Settings.
In Supabase Dashboard → Auth → Providers → Email, disable 'Confirm email' for development; for production configure custom SMTP in Auth → SMTP Settings using your Resend API key
`new row violates row-level security policy` on profiles INSERTWhy: If you add a profiles table with RLS enabled but forget the INSERT policy, the profile creation step in the Auth Callback Route silently fails. The user is authenticated but has no profile row.
Fix: Add an INSERT policy to the profiles table: CREATE POLICY "users_insert_profile" ON profiles FOR INSERT WITH CHECK (auth.uid() = id).
Add an INSERT policy to the profiles table: CREATE POLICY users_insert_profile ON profiles FOR INSERT WITH CHECK (auth.uid() = id)
Template vs. custom — the honest call
A forked template gets you far, fast. Here's where it holds up, and where you'll outgrow it.
The template is enough when
- SaaS MVP that needs complete auth — signup, login, protected dashboard — shipped in one afternoon
- Learning Supabase auth patterns before building a production system
- Multi-user app where each user owns their own data and RLS handles the isolation
- Investor demo prototype with real login so you can demo without hardcoded test accounts
Go custom when
- You need Stripe billing tied to auth — subscription gating requires webhook processing and DB sync that V0 won't fully scaffold
- SAML SSO for enterprise customers requires a dedicated identity provider integration
- Advanced session management such as device list, per-device session revocation, or forced logout
- Compliance-grade audit logging of every auth event for SOC 2 or HIPAA requirements
RapidDev extends this V0 Supabase Auth starter with your schema, RLS policies, and business logic — a complete backend for your SaaS, usually in 2–3 days.
Frequently asked questions
Is the Supabase Auth Starter template free to use?
Yes. Forking v0 community templates is free. You spend V0 credits only when you send prompts to the chat to customize the template. Design Mode changes are also free.
Can I use this template commercially?
Yes. V0 community templates are available for commercial use. You own the generated code and can use it in any product, including paid SaaS applications. Check v0.dev's terms of service for the full licensing details.
Why does my fork show blank screens or import errors in V0 preview?
The most common cause is the `@supabase/ssr` package failing in V0's esm.sh preview sandbox. This is a known limitation — the package uses server-side APIs the preview can't run. Click Share → Publish to Production and test on the live Vercel URL instead. The deployed app works correctly.
I signed up but never received a confirmation email — what's wrong?
Supabase's free tier limits confirmation emails to 4 per hour per project, and they frequently land in spam. For development, disable email confirmation in Supabase Dashboard → Authentication → Providers → Email. For production, configure a custom SMTP provider like Resend or Postmark in Supabase Dashboard → Auth → SMTP Settings.
Should I use @supabase/auth-helpers-nextjs instead of @supabase/ssr?
No. @supabase/auth-helpers-nextjs is deprecated and should not be used in new projects. This template already uses the correct @supabase/ssr package which Supabase now recommends for all Next.js App Router projects.
How do I connect a database table to the protected dashboard?
After the Protected Dashboard renders a confirmed user, call supabase.from('your_table').select('*').eq('user_id', user.id) in a Server Component. Add a Row Level Security policy so users can only see their own rows: CREATE POLICY 'users see own data' ON your_table FOR SELECT USING (auth.uid() = user_id). The medium-difficulty prompt in this playbook walks through this for the profiles table.
Can RapidDev set up this Supabase auth template for my project?
Yes. RapidDev sets up the full Supabase auth flow — login, signup, protected routes, RLS policies, and your schema — typically in 2–3 days.
Outgrowing the template?
RapidDev turns v0 prototypes into production apps — real auth, database, and payments — at $13K–$25K.
Book a free consultation30-min call. No commitment.