SaaS Builder Lab — Build Your First AI-Powered SaaS

Your Idea

Tech Stack

Setup

Structure

Database

Features

Test

Launch

⚡ Full-Stack SaaS Tech Stack

Every layer you need to ship a production SaaS — all free to start. Upgrade when you have paying users.

Layer	Technology	Free Tier	What It Does	When to Upgrade
Frontend	Next.js 15 (App Router)	FREE	React framework with server-side rendering, routing, and API routes. The one framework that does everything.	Never — it scales to millions of users.
Language	TypeScript	FREE	Type-safe JavaScript. Catches errors at compile time, not in production. Required for maintainable SaaS.	Never.
Styling	Tailwind CSS	FREE	Utility-first CSS framework. Write styles as class names directly in JSX. No context switching.	Never — pairs with shadcn/ui for components.
Database + Auth	Supabase	FREE 500MB · 50K users	PostgreSQL database with built-in auth, Row Level Security, real-time subscriptions, storage, and edge functions.	$25/mo at ~50K active users or 8GB.
AI Provider	Groq AI	FREE 14,400 req/day	Fastest inference available. Runs LLaMA 3.3 70B. OpenAI-compatible API — swap providers by changing one URL.	$0.59/M tokens input — only when you have usage.
Deployment	Vercel	FREE Hobby plan	Zero-config deployment for Next.js. Push to GitHub → live in 45 seconds. Automatic preview URLs per branch.	$20/mo Pro for custom domains + team.
Version Control	GitHub	FREE	Store code, trigger Vercel deployments, manage issues and pull requests. The source of truth for your project.	Never for solo projects.
ORM / Query	Supabase JS SDK	FREE	Type-safe client for Supabase queries. Works on both server and client. No raw SQL needed for common operations.	Never — use SQL for complex queries.
UI Components	shadcn/ui	FREE	Copy-paste component library built on Radix UI + Tailwind. You own the code — no black box dependency.	Never — add Tremor for data viz if needed.
Icons	Lucide React	FREE	600+ crisp SVG icons as React components. Tree-shakeable — only bundle what you use.	Never.

💰 Monthly Cost by Growth Stage

💡 Idea Stage

/month

• Next.js — free
• Supabase Free tier
• Groq AI free tier
• Vercel Hobby
• GitHub Free

🚀 Early Traction

$25

/month

• Supabase Pro ($25)
• Groq AI (~$5 usage)
• Vercel Hobby still fine
• Domain ($10/yr)

📈 Growing

$70

/month

• Supabase Pro ($25)
• Vercel Pro ($20)
• Groq AI (~$20 usage)
• Resend email ($5+)

🏢 Scaling

$200+

/month

• Supabase Team ($599)
• Or self-hosted PG
• Multiple AI providers
• CDN, monitoring

✅ SaaS Pre-Launch Checklist

🔐 Auth & Security

□All protected routes redirect unauthenticated users to /login

□Row Level Security enabled on ALL database tables

□GROQ_API_KEY has no NEXT_PUBLIC_ prefix (server-only)

□.env.local is in .gitignore — never committed

□AI routes use server-side only (route.ts, not client)

🗄️ Database

□Supabase project created in correct region

□All tables have RLS policies (not just enabled)

□user_id columns reference auth.users(id)

□Indexes on user_id and created_at for performance

□Schema tested with a real account before launch

🤖 AI Integration

□System prompt clearly defines AI's role and constraints

□User inputs sanitized before adding to prompts

□Error handling if AI provider is down (try/catch)

□AI responses validated before saving to DB

□Rate limiting considered for API route

🚀 Deployment

□All env vars set in Vercel project settings

□Supabase URL in CORS allowed origins

□Auth redirect URLs set in Supabase Dashboard

□Production deployment tested end-to-end

□Custom domain configured (or Vercel subdomain noted)

🧪 Functional Testing

□New user registration → email confirmation → login works

□Logged-in user can create, read, update, delete their data

□AI feature generates output end-to-end in production

□User A cannot see or edit User B's data

□Mobile layout tested on actual device

📣 Marketing Ready

□Landing page clearly states what the product does

□Call-to-action above the fold ("Sign up free")

□LinkedIn/Twitter launch post drafted and ready

□Target communities identified (Reddit, Slack, Discord)

□Feedback form or email configured for early users

⚖️ 10 Commandments of AI SaaS

Never expose API keys to the browser

Any key with NEXT_PUBLIC_ is in your client bundle. Any user can steal it. AI keys go in server-only code (route handlers, server actions) — never in components.

Enable Row Level Security on every table

RLS is not optional. Without it, any authenticated user can read every row in every table via the Supabase JS SDK. Enable RLS + write policies before inserting any real data.

Stay provider-agnostic by default

Use an AI provider with an OpenAI-compatible API (Groq, Together, OpenRouter). That way you switch providers by changing one URL — not your entire codebase.

Always wrap AI calls in try/catch

AI providers go down. Rate limits happen. Network timeouts are real. Unhandled promise rejections in production = white screens and angry users. Catch everything, return graceful errors.

Free tier first — validate before paid

Run on $0/month until you have users who pay. Supabase free (500MB), Groq free (14K req/day), Vercel Hobby — enough to validate any SaaS idea. Add cost only when you add revenue.

Sanitize all user input before prompts

Prompt injection is the AI equivalent of SQL injection. A user can type "Ignore all previous instructions…" and hijack your AI's behavior. Trim, validate, and constrain user inputs before inserting into system or user prompts.

Engineer your system prompt, not your UI

The system prompt is where AI product quality lives. 90% of your AI behavior is determined by a well-crafted system prompt. Spend more time on prompt engineering than on UI components.

Commit .env.local to .gitignore immediately

The #1 security mistake by beginners. Create .gitignore before your first commit. Once a secret is in git history, it's compromised — even after deletion.

Test the auth flow on every deployment

Auth is the most common source of production bugs. After every deployment, manually: (1) register new user, (2) confirm email, (3) log in, (4) log out, (5) access a protected page unauthenticated.

Ship ugly first, polish later

No one has ever failed because their MVP was too ugly. They fail because they spent 3 months perfecting a UI no one wants. Get to "working + deployed" in days, not months. Real users give better feedback than imagined ones.

🔑 Common Errors & Fixes

Error	Cause	Fix
AuthSessionMissingError	No active session — user not logged in or session expired	Check `auth.getUser()` before accessing protected routes. Middleware re-auth.
new row violates RLS policy	INSERT denied because user_id doesn't match auth.uid()	Make sure you're passing `user_id: user.id` in insert. RLS policy must match auth.uid().
GROQ_API_KEY not defined	Environment variable missing in deployment	Add GROQ_API_KEY in Vercel → Project → Settings → Environment Variables. Redeploy.
NEXT_REDIRECT error in try/catch	redirect() throws internally in Next.js 15 — caught by your try/catch	Never wrap redirect() in try/catch. Call it outside the catch block.
fetch failed (ERR_CERT_*)	Invalid SUPABASE_URL — missing https:// or wrong project ref	Copy URL from Supabase Dashboard → Project Settings → API. Include full URL with https://.
AuthApiError: invalid API key	Wrong anon key or key copied with whitespace	Copy anon key from Supabase Dashboard → Project Settings → API → anon public.
Module not found '@/lib/supabase'	Import path wrong or file not created	Create `lib/supabase/client.ts` and `lib/supabase/server.ts`. Check tsconfig paths.