# Auth options for Vite + React (SPA)

In **Next.js**, **NextAuth.js** (now **Auth.js**) is the standard: it gives you OAuth (Google, GitHub, etc.), sessions, callbacks, and JWT/cookies on the server.

For a **Vite + React** app (client-side SPA), there is no single “NextAuth for Vite.” You pick by how much you want to host yourself vs use a service.

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## 1. **Firebase Authentication** (what this project uses)

- **What it is:** Google’s auth service; add SDK, configure providers (e.g. Google), get sign-in in the browser.
- **Pros:** Free tier, no backend required for basic “Sign in with Google,” works great with Vite + React.
- **Cons:** You’re tied to Firebase; for custom session logic you still need your own backend.
- **Use when:** You want the fastest “Sign in with Google” (or email link, etc.) with no backend.

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## 2. **Clerk**

- **What it is:** Hosted auth (like Auth0) with pre-built React components and APIs.
- **Pros:** Drop-in `<SignIn />` / `<SignUp />`, many providers, user management dashboard, works with any frontend (including Vite + React).
- **Cons:** Paid after free tier; vendor lock-in.
- **Use when:** You want a “NextAuth-like” experience (components + dashboard) without running your own auth server.

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## 3. **Auth0** (Okta)

- **What it is:** Hosted identity platform; SDK + hosted login pages or embedded UI.
- **Pros:** Enterprise-ready, many providers, fine-grained controls.
- **Cons:** Can be heavy and costly for small apps.
- **Use when:** You need enterprise features or already use Okta.

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## 4. **Supabase Auth**

- **What it is:** Auth layer from Supabase (DB + realtime + storage).
- **Pros:** Google, magic link, email/password; integrates with Supabase DB and RLS.
- **Cons:** Makes most sense if you use Supabase for data.
- **Use when:** Your backend (or “BaaS”) is Supabase.

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## 5. **Auth.js (formerly NextAuth) + your own backend**

- **What it is:** The same library NextAuth uses; you run it on **Express**, **Fastify**, or another Node server. Your Vite app is just a client that talks to that API.
- **Pros:** Full control, sessions/callbacks like in Next.js, same mental model as NextAuth.
- **Cons:** You build and run the backend; CORS and cookie/session handling for SPA.
- **Use when:** You want “NextAuth” behavior (sessions, callbacks, multiple providers) with an Express (or similar) API and a Vite React frontend.

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## Summary

| Need                         | Good fit              |
|-----------------------------|------------------------|
| “Sign in with Google” only  | **Firebase Auth**      |
| Pre-built UI + dashboard    | **Clerk**              |
| Backend is Supabase         | **Supabase Auth**      |
| NextAuth-style + Express    | **Auth.js on Express** |

This app uses **Firebase Auth** for a simple, backend-free Google sign-in that works well with Vite + React.