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How to Build a Complete SaaS for $0 Using Free Tools in 2026

#saas #free #opensource #productivity

The $0 SaaS Stack

Everyone says you need money to build a SaaS. They're wrong. In 2026, you can build, deploy, and scale a complete SaaS application without spending a single dollar.

The Architecture 

Users → Vercel (Next.js) → Supabase (Auth + DB) → Cloudflare (DNS + CDN)
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Total cost: $0/month

Step 1: Set Up Your Project 

npx create-next-app@latest my-saas --typescript --tailwind --app
cd my-saas
npm install @supabase/supabase-js @supabase/auth-helpers-nextjs
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Step 2: Database with Supabase (Free)

Create a project at supabase.com, then set up your schema:

CREATE TABLE projects (
  id UUID DEFAULT gen_random_uuid() PRIMARY KEY,
  user_id UUID REFERENCES auth.users(id),
  name TEXT NOT NULL,
  description TEXT,
  created_at TIMESTAMPTZ DEFAULT NOW()
);

ALTER TABLE projects ENABLE ROW LEVEL SECURITY;

CREATE POLICY "Users can view own projects" ON projects
  FOR SELECT USING (auth.uid() = user_id);
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Step 3: Authentication (Free) 

'use client'
import { createClientComponentClient } from '@supabase/auth-helpers-nextjs'

export default function Login() {
  const supabase = createClientComponentClient()

  const handleLogin = async () => {
    await supabase.auth.signInWithOAuth({
      provider: 'google',
      options: { redirectTo: `${location.origin}/auth/callback` }
    })
  }

  return <button onClick={handleLogin}>Sign in with Google</button>
}
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Supabase Auth: 50,000 monthly active users free 🎉

Step 4: API Routes (Free) 

// app/api/projects/route.ts
import { createRouteHandlerClient } from '@supabase/auth-helpers-nextjs'
import { cookies } from 'next/headers'
import { NextResponse } from 'next/server'

export async function GET() {
  const supabase = createRouteHandlerClient({ cookies })
  const { data } = await supabase.from('projects').select('*')
  return NextResponse.json(data)
}

export async function POST(request: Request) {
  const supabase = createRouteHandlerClient({ cookies })
  const { name, description } = await request.json()
  const { data } = await supabase
    .from('projects')
    .insert({ name, description })
    .select()
    .single()
  return NextResponse.json(data)
}
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Step 5: Deploy to Vercel (Free) 

npx vercel --prod
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Vercel free: 100GB bandwidth, auto HTTPS, global CDN.

Step 6: Add AI Features

Use MonkeyCode for AI-powered features in your SaaS — free tier available.

Complete Free Tier Summary

Service Purpose Free Limit
Vercel Hosting 100GB BW
Supabase DB + Auth 500MB + 50K users
Cloudflare DNS + CDN Unlimited
GitHub Source control Unlimited
GitHub Actions CI/CD 2,000 min/mo
MonkeyCode AI coding Free tier

Total: $0/month 🚀

When to Upgrade

You only need to pay when:

  • 📈 >50K monthly active users
  • 💾 Database >500MB
  • 🔄 >100GB bandwidth

By that point, you should be making revenue!

What's your free SaaS stack? Share in the comments! 👇

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