The exact process we use to ship SaaS MVPs in 4-6 weeks. No fluff, no shortcuts that break later.
By David Friedman, Founder of AppBrewers
I have shipped 50+ SaaS MVPs in the last five years. The ones that succeeded had one thing in common: they launched fast with the minimum viable product, then iterated based on real user feedback. Here is the exact 6-week process we use at AppBrewers to get founders from idea to first paying customer.
Week 1: Validate Before You Build
The 100 Euro Validation Test
Before writing a single line of code, spend 100 Euro and one week to answer three questions:
- Does anyone want this? -- Create a landing page with a waitlist. Run 50 Euro of ads. If fewer than 10 people sign up, kill the idea.
- Will they pay? -- Email the waitlist. Offer a pre-order at 50% off. If fewer than 3 people pay, the problem is not painful enough.
- Can I build this? -- Map the core feature. If it requires more than 3 screens, it is too big for v1.
Tools we use:
- Carrd or Typedream for landing pages (0-19 Euro)
- Brevo or Mailchimp for email (free tier)
- Meta Ads or Google Ads for traffic (50 Euro test budget)
Week 2: Design the Core Loop and Tech Stack
Define Your Core Loop
Every successful SaaS has a core loop -- the 3-step action users repeat:
| SaaS | Core Loop |
|---|---|
| Slack | Join channel -> Send message -> Get notified |
| Notion | Create page -> Edit content -> Share link |
| Stripe | Create product -> Add payment -> Receive funds |
Your job: Define your core loop in one sentence. Everything else is v2.
Choose Your Stack
For 2026, our recommendation for SaaS MVPs:
| Layer | Technology | Why |
|---|---|---|
| Framework | Next.js 15 | Server components, App Router, Edge |
| Database | Firebase Firestore | Real-time, scalable, managed |
| Auth | Firebase Auth | Email, Google, Apple sign-in out of the box |
| Billing | Stripe | Subscriptions, Checkout, Customer Portal |
| Hosting | Firebase App Hosting | Zero config, automatic scaling |
| UI | shadcn/ui + Tailwind | Production-ready components |
Total monthly cost at launch: 0-50 Euro (Firebase free tier + Stripe fees)
Week 3: Build Auth and Database
What to Build
- Firebase Auth with email/password and social login
- Firestore database schema for users, subscriptions, and core data
- Security rules (test these -- they are your firewall)
- Basic user profile page
What NOT to Build
- Admin dashboard (v2)
- Team/organization features (v2)
- Advanced analytics (v3)
- Mobile app (only if core loop requires it)
Week 4: Build the Core Feature
The 3-Screen Rule
Your MVP should have exactly 3 screens:
- Landing/Auth -- Sign up, log in, password reset
- Core Feature -- The one thing users pay for
- Settings/Billing -- Profile, subscription, logout
Example: AI Receptionist SaaS
| Screen | Function |
|---|---|
| Landing | Pricing, demo video, sign up |
| Dashboard | Connect WhatsApp, configure auto-replies, view conversations |
| Settings | Billing (Stripe), profile, logout |
Everything else -- analytics, multi-location, custom branding -- is v2.
Week 5: Add Billing and Admin
Stripe Integration
- Checkout for subscription sign-up
- Customer Portal for subscription management
- Webhooks for payment events
- Firestore sync for subscription status
Basic Admin Dashboard
- User list
- Subscription status
- Revenue metrics (simple, no complex charts)
Week 6: Launch to 10 Users
The Soft Launch Checklist
- [ ] Core loop works without bugs
- [ ] Stripe charges successfully
- [ ] Password reset email arrives
- [ ] Mobile responsive
- [ ] Google Analytics installed
- [ ] Error tracking (Sentry) active
- [ ] Privacy policy and ToS pages live
- [ ] First user can sign up, pay, and use the product without help
Where to Find First Users
- Your waitlist -- Email everyone who signed up during validation
- Reddit -- Post in relevant subreddits (r/SaaS, r/entrepreneur, r/webdev)
- Twitter/X -- Share your launch thread
- Product Hunt -- Schedule for a Tuesday at midnight PST
- Indie Hackers -- Post a milestone story
Cost Breakdown
| Stage | DIY (Code) | Agency (AppBrewers) |
|---|---|---|
| Validation | 100 Euro | 500 Euro |
| Design | 0 (wireframe) | 2,000-4,000 Euro |
| MVP Build | 3,000-8,000 Euro | 8,000-15,000 Euro |
| Hosting | 0-50/month | Included for 60 days |
| Launch | 0 | Included |
| Total v1 | 3,100-8,100 Euro | 10,500-16,500 Euro |
Read our full cost breakdown: SaaS Development Cost in 2026
Metrics to Track from Day 1
| Metric | Target | What It Tells You |
|---|---|---|
| Signup conversion | >20% | Is your landing page clear? |
| Activation rate | >40% | Do users complete the core loop? |
| Retention (Day 7) | >20% | Is the product sticky? |
| NPS | >40 | Do users love it enough to recommend? |
| Churn (monthly) | <5% | Is pricing right? |
What to Build Next
Based on data, not gut:
- Low activation -> Simplify onboarding
- Low retention -> Add notifications or reminders
- High churn -> Interview churned users
- High NPS -> Build referral program
Common Mistakes
Building Too Much in v1
Founders want AI, analytics, and integrations in the MVP. The result: 6-month build, 40,000 Euro spent, zero customers.
Fix: Strip to 3 screens. Launch in 4 weeks.
Ignoring Billing
Founders say we will add billing later. Later never comes. If you do not charge from day one, you do not know if anyone will pay.
Fix: Add Stripe in week 5. Even if it is just a 5 Euro/month plan.
Perfectionism
Just one more feature before launch. This kills more startups than bad ideas.
Fix: Launch when it is embarrassing. Fix in production.
Need Help Building?
We have shipped 50+ SaaS MVPs. If you want it done right, fast:
Originally published on the AppBrewers Blog.
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