How to Build a SaaS App from Scratch in 2026: Complete Step-by-Step Guide

1Define Your SaaS Idea

Validate before building. Use a landing page + waitlist approach. Ship a simple page that explains the product and captures emails. Tools like Framer ($4/mo) or a static site on Vercel work great. If you get signups, you have signal to build.

Framer — $4/mo landing pages

Vercel — free static hosting

2Choose Your Tech Stack

Next.js + Supabase + Vercel is the most popular combo in 2026. Next.js is the #1 React framework (used by Netflix, TikTok, Hulu). Supabase has 80,000+ GitHub stars. TypeScript is used by 43.4% of professional devs (Stack Overflow 2025). Don't overthink it—pick a proven stack and ship.

3Set Up Your Project

Create a new Next.js app with the App Router and Turbopack. Enable TypeScript strict mode. Then add shadcn/ui and configure Tailwind v4.

npx create-next-app@latest my-saas --typescript --tailwind --eslint --app --src-dir
cd my-saas
npx shadcn@latest init

In tsconfig.json, set "strict": true. Install components as needed: npx shadcn@latest add button card input.

4Build Your Database

Create a Supabase project (free tier: 500MB, Pro: $25/mo for 8GB). Design your schema: users (or use auth.users), subscriptions, and your app-specific tables. Enable Row Level Security (RLS) on every table and write policies. Use migrations so your schema is versioned and reproducible.

• Create project in Supabase dashboard
• Add tables: e.g. subscriptions, workspaces
• Enable RLS and create policies (e.g. users can only read their own rows)
• Run migrations via SQL or Supabase CLI

Supabase — PostgreSQL, 500MB free / 8GB on Pro

5Add Authentication

Use Clerk (free: 10K MAUs) or Supabase Auth (free). Set up OAuth with Google and GitHub. Protect routes with middleware.ts so unauthenticated users are redirected to sign-in.

Clerk — 10K MAUs free

Supabase Auth — free

6Build Core Features

Use Server Components for data fetching and Server Actions for mutations. Validate forms with React Hook Form + Zod. Keep client components minimal; push logic to the server for better performance and security.

• Server Components: fetch data in async components, no useEffect
• Server Actions: form submissions and mutations with revalidation
• React Hook Form + Zod: type-safe validation and good DX

7Add Payments with Stripe

Stripe has no monthly fee—you pay 2.9% + $0.30 per transaction. Set up Products and Prices in the Dashboard, create Checkout sessions for one-time or subscription flows, and handle checkout.session.completed and subscription webhooks. Store subscription status in your DB and gate features accordingly.

Stripe — 2.9% + $0.30 per transaction, no monthly fee

8Set Up Email

Use Resend (free: 3,000 emails/month) with React Email for templates. Send welcome emails, password reset, and transactional emails via the Resend API. Verify your domain for better deliverability.

Resend — 3,000 emails/month free

9Add Analytics & Monitoring

PostHog gives you 1M events/month free for product analytics (funnels, retention, session replay). Sentry offers 5K errors/month free for error tracking. Add both early so you can fix issues and understand user behavior from day one.

PostHog — 1M events/mo free

Sentry — 5K errors/mo free

10Deploy to Production

Deploy to Vercel (free Hobby tier; Pro $20/mo). Connect your repo, set environment variables for Supabase, Stripe, Clerk, Resend, PostHog, and Sentry. Add a custom domain and configure DNS (e.g. CNAME to Vercel). Enable HTTPS—Vercel does this automatically.

Vercel — free Hobby, Pro $20/mo

11Post-Launch Essentials

Add SEO basics: meta tags, Open Graph, a sitemap, and robots.txt. Keep monitoring PostHog and Sentry. Collect user feedback (in-app or email) and iterate. Stripe processes payments for millions of businesses—you're in good company; focus on product and distribution.

• SEO: title, description, og:image, sitemap, robots
• Monitoring: fix errors and watch key funnels
• Feedback: simple survey or support channel
• Iterate: ship small improvements regularly

Timeline: Week 1–4