How to Build a SaaS with Nuxt 4, better-auth, and Polar

Building a SaaS on Nuxt is more approachable than ever. AI can scaffold pages, forms, and CRUD in minutes. The parts that still decide whether you ship are the same: auth, payments, data, and security.

This guide outlines a modern stack: Nuxt 4, better-auth, and Polar.

The product shape you are aiming for

Most early SaaS apps need:

1. Users who can sign up and sign in
2. A paid plan (one-time or subscription)
3. An authenticated app area
4. An admin path for support and abuse cases
5. Deployability without locking into one host

Everything else is product-specific.

Step 1: Start with Nuxt 4 as the application shell

Nuxt 4 gives you SSR/SPA flexibility, file-based routing, server routes, and a mature module ecosystem.

For a SaaS, prefer:

• TypeScript everywhere
• Server routes for webhooks and privileged actions
• Clear separation between marketing site and app (or shared layers if you use a monorepo)

Step 2: Put better-auth at the center of identity

better-auth is a strong fit when you want email/password, social providers, and modern auth features without owning a custom auth framework.

Minimum production checklist:

• Secure session cookies
• Email verification / password reset flows
• Rate-limited auth endpoints
• Role or admin flag for privileged actions

Do not treat auth as “done” when the login page works. Treat it as done when sessions, resets, and abuse controls exist.

Step 3: Monetize with Polar as Merchant of Record

Polar is compelling for indie and solo founders because it can act as Merchant of Record — reducing tax and payment ops overhead compared to wiring everything yourself.

You will still need:

• Product/price configuration
• Checkout links or embedded checkout
• Webhook verification
• Mapping Polar customers to your users

The webhook handler is the heart of billing correctness. Design it to be idempotent from day one.

Step 4: Add the unglamorous SaaS essentials

These rarely show up in Twitter demos and always show up in real products:

• Database migrations you trust
• Admin user management
• Basic auditability for support
• Security headers and rate limits
• Error monitoring

This is also where a polished starter kit pays for itself.

Where a starter kit saves weeks

You can assemble Nuxt + better-auth + Polar yourself. Many people should.

You should buy time when:

• You have already rebuilt auth/payments twice
• You want layer-based architecture instead of inventing structure under deadline
• You would rather ship product features this month

That is the problem Nuxt Starter Kit is built to solve: a production-minded Nuxt 4 SaaS foundation with auth, Polar payments, admin, and security already wired.

Suggested build order (solo founder)

1. Auth + protected routes
2. Database models for users/plans
3. Checkout + webhook → entitlement
4. Core product loop
5. Admin + monitoring
6. Marketing pages and SEO content

If step 1–3 are still open after a week, your foundation is the bottleneck — not your idea.

Next steps

• Browse the docs for the kit’s architecture
• Compare scope on pricing
• Or start from scratch with Nuxt, better-auth, and Polar using the checklist above