Launching a SaaS MVP: From Idea to Production in 90 Days

Every developer I know has at least one SaaS idea sitting in a notes app somewhere. The difference between those who ship and those who don't is rarely technical ability — it's execution. After launching multiple MVPs for both my own products and clients — including PeptiSync — I've settled on a repeatable 90-day framework that maximizes learning while minimizing wasted effort.

This guide walks through the entire lifecycle: scoping, architecture, building, launching, and iterating. If you follow it, you'll have a working product in front of real users by day 90.

Phase 1: Scoping and Validation (Days 1–14)

The biggest mistake founders make is building too much before talking to users. Your goal in the first two weeks isn't code — it's clarity.

Define the Core Loop

Every SaaS product has a single moment of value — the instant a user thinks "this is worth paying for." Strip everything else away until only that moment remains.

For example, if you're building an invoicing tool, the core loop isn't "user creates account, sets up company profile, adds clients, creates invoice, sends invoice, tracks payment." It's "user sends invoice and gets paid." Everything else is overhead.

Write down the core loop in five steps or fewer. If you can't, you haven't scoped tightly enough.

Validate with a Landing Page

Before writing a single line of backend code, create a landing page describing the product with a "Get Early Access" email form. Run a small ad campaign ($200–$500) or post in relevant communities. Measure conversion rate from visitor to signup.

I typically look for 3–5% conversion as a signal that the problem is real. Below 1% means the messaging or the problem itself needs work.

Choose Your Weapons

For a 90-day MVP, speed matters more than scalability. Here's my recommended tech stack:

• Frontend: Next.js with Tailwind CSS
• Backend/Database: Firebase (Auth, Firestore, Cloud Functions)
• Payments: Stripe
• Deployment: Vercel
• Email: Resend or SendGrid

This stack lets you move fast because Firebase handles authentication, database, and serverless functions out of the box. You don't need to provision servers, configure databases, or manage sessions.

Phase 2: Building the MVP (Days 15–60)

This is where most projects stall. The key is ruthless prioritization.

Authentication and User Management

Firebase Auth integrates with Next.js through next-firebase-auth or the Firebase client SDK. Start with email/password and Google OAuth — that covers 90% of users.

```tsx import { getAuth, signInWithPopup, GoogleAuthProvider } from 'firebase/auth';

const auth = getAuth(); const provider = new GoogleAuthProvider();

export async function signInWithGoogle() { const result = await signInWithPopup(auth, provider); return result.user; } ```

The Paywall

Set up Stripe with Firebase Cloud Functions to handle webhooks. The critical webhook events are checkout.session.completed, customer.subscription.updated, and invoice.payment_failed.

```typescript export const stripeWebhook = functions.https.onRequest(async (req, res) => { const sig = req.headers['stripe-signature'] as string; const event = stripe.webhooks.constructEvent(req.body, sig, endpointSecret);

if (event.type === 'checkout.session.completed') { const session = event.data.object; await grantAccessToUser(session.client_reference_id!, session.subscription as string); }

res.json({ received: true }); }); ```

Feature Flags

Ship features behind flags from day one. I use a simple Firestore document with feature toggles. This lets you roll out functionality gradually without redeploying.

``typescript const features = await getDoc(doc(db, 'config', 'features')); if (features.data()?.exportCSV) { // render export button } ``

The UI: Bootstrap with a Component Library

Don't build UI from scratch. Use Shadcn/UI or Mantine for polished components. Your goal is functional, not beautiful. Ugly products that solve real problems win over beautiful products that solve nothing.

Phase 3: Pre-Launch (Days 61–75)

Testing with Real Users

Recruit 5–10 beta testers from your early-access list. Give them the product for free in exchange for 15-minute weekly feedback calls. Watch them use the product without guiding them. Where they hesitate or get confused is where you need to improve.

Performance and Error Monitoring

Install Sentry for error tracking and set up Firebase Performance Monitoring. Fix errors before they become churn reasons. A single broken login flow can cost you 30% of signups.

Set Up Analytics

Track the metrics that matter: signup conversion, activation rate (user completes core loop), retention (user returns within 7 days), and revenue. I use PostHog for product analytics because it's free for small projects and self-hostable.

Phase 4: Launch and Iterate (Days 76–90)

Launch is a milestone, not a finish line.

The Launch Checklist

• Custom domain configured on Vercel
• SSL working
• Stripe test mode switched to live mode
• Analytics verified
• Error monitoring active
• Terms of Service and Privacy Policy pages live
• Contact form or support email ready

Where to Launch

• Product Hunt: Schedule for a Tuesday or Thursday
• Hacker News: Share as a "Show HN" with a story about building it
• Indie Hackers: Write about your journey and metrics
• Reddit: Post in relevant subreddits (r/SaaS, r/startups)

The First Week Post-Launch

Your inbox will be quiet. That's normal. Spend the first week talking to every single signup. Ask them what they expected, what's missing, and whether they'd be disappointed if the product disappeared.

If no one would be disappointed, you haven't found product-market fit yet. Keep iterating.

Conclusion

Ninety days is enough time to build something real if you stay disciplined about scope. The hardest part isn't the code — it's saying no to the features that seem important but don't serve the core loop. Ship the smallest possible version of your idea, put it in front of users, and let their feedback guide what comes next.

Building something and need a technical partner? Let's talk about your project. I help founders go from idea to launched MVP with clean, maintainable code.

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