The hardest part of starting a SaaS in 2026 isn't writing code - it's choosing the stack. Every layer has five defensible options and a dozen strong opinions. This is an opinionated, boringly reliable stack for building a Next.js SaaS: the choices that let you ship fast, scale sanely, and not rewrite everything in six months. Where there's a real fork, I'll name the alternative and when to take it.
The stack at a glance
| Layer | Pick | Strong alternative |
|---|---|---|
| Framework | Next.js (App Router) | - |
| Language | TypeScript (strict) | - |
| Styling | Tailwind CSS v4 | CSS Modules |
| Components | shadcn/ui | Build your own |
| Auth | Auth.js | Clerk (managed) |
| Database | Postgres (Neon) + Drizzle | Supabase / Prisma |
| Payments | Stripe | Dodo / Lemon Squeezy (MoR) |
| AI | Vercel AI SDK + Claude | - |
| Resend | Postmark | |
| Hosting | Vercel | - |
Framework, language, and styling
Next.js with the App Router is the default for a reason: server components, server actions, and a single codebase for your marketing site and app. TypeScript in strict mode is non-negotiable for anything you'll maintain - the compile-time safety pays for itself the first time you rename a field. Tailwind CSS v4 for styling, with its @theme token system, makes an entire product reskinnable from a handful of variables and keeps styles colocated with markup.
Auth and database
For auth, Auth.js (formerly NextAuth) is the flexible, self-hosted default; reach for Clerk when you'd rather pay to never think about auth UI, sessions, and organizations again. For data, Postgres is the safe forever-choice - Neon and Supabase both give you serverless Postgres with generous free tiers. Pair it with Drizzle (typed, SQL-first, light) or Prisma (batteries-included, more magic). The through-line: pick managed Postgres and a typed query layer, and you won't outgrow it.
Payments
Stripe is the default and the most capable, and the right pick if you're comfortable handling sales tax and VAT yourself (or with a tax add-on). If you'd rather offload tax and compliance entirely, a merchant-of-record provider like Dodo Payments or Lemon Squeezy handles the tax paperwork globally in exchange for a slightly higher fee - often worth it for a small team selling internationally. Decide based on whether you want to own tax compliance or rent it.
AI, email, and hosting
If your SaaS has an AI feature, the Vercel AI SDK is the standard way to build it - one API across providers, first-class streaming, and an easy swap between models. Point it at Claude for strong reasoning and a clean developer experience. For transactional email (receipts, invites, password resets), Resend is the modern default with a great DX and React-based email templates. And for hosting, Vercel is the path of least resistance for Next.js - zero-config deploys, preview URLs, and edge/serverless handled for you.
- AI: Vercel AI SDK + Claude - streaming, provider-agnostic, swap models in one line
- Email: Resend - transactional email with React templates
- Hosting: Vercel - zero-config Next.js deploys and preview URLs
- Analytics: Vercel Analytics or PostHog when you need product analytics + flags
The best stack is the one you don't have to think about. Every pick here is chosen to be reliable and swappable, not clever - so you spend your energy on the product, not on infrastructure decisions you'll second-guess at 2am.
Skip the setup - TheKitBase templates ship on exactly this stack
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