Como Crear un SaaS desde Cero en 2026: Guia Completa

90% of startups fail. Among SaaS companies, the percentage is even higher if you count those that never land a single paying customer. But the ones that survive have something in common: they started small, validated fast, and didn't spend more than they had to.

If you want to know how to build a SaaS in 2026, this article gives you what most guides don't: a concrete tech stack (not "pick whatever you like"), real costs in euros (not absurd dollar ranges), and the steps that actually matter, with the honesty to tell you what can go wrong too.

We build SaaS products for clients every week at our development studio. This is what we've learned about how to build a SaaS that actually works.

What Is a SaaS and Why Does Everyone Want to Build One

If you're wondering what a SaaS is, the answer is straightforward: a SaaS (Software as a Service) is cloud-based software that users access from a browser and pay for through a recurring subscription. It's not installed. It's not downloaded. It's used.

Examples of SaaS you probably use every day: Notion for documents, Slack for communication, Canva for design, Stripe for payments, Google Workspace for email. They all work the same way: you log in, pay monthly or annually, and the software updates itself.

Why is the SaaS business model so attractive? Three reasons:

• Recurring revenue: You don't sell once. You charge every month. A customer paying 50 euros/month is 600 euros/year without having to sell them anything again.
• Scalability: The cost of serving one more user is close to zero. The same software serves 10 or 10,000 customers.
• Valuation: SaaS businesses are valued at 5x to 15x their annual recurring revenue. A SaaS making 100,000 euros/year can sell for 500,000 to 1.5 million.

Javier, a frontend developer at an agency, figured it out when he started doing the math. "I had a client paying me 3,000 euros per project, every three months. A SaaS with 100 users at 30 euros/month would give me the same income, but predictably and without depending on a single client." In January 2026 he launched his first micro SaaS. Six months later he's making 2,800 euros/month with 93 users.

If you want to see how much it costs to build a web app or SaaS, we have a complete guide to web development pricing with real ranges.

Micro SaaS: The Smartest Way to Start

You don't need a billion-dollar idea. You don't need investors. You don't need a 10-person team. If you want to learn how to build a SaaS without going broke, what you need is a micro SaaS.

A micro SaaS is a small SaaS product focused on solving ONE specific problem for ONE specific niche. It can be built and maintained by a single person (or a very small team). Think of a tool that automates invoice sending for physical therapists, or a metrics dashboard for Shopify stores, or a bot that manages reservations for restaurants.

Why micro SaaS before an ambitious SaaS?

• Lower upfront investment: A micro SaaS MVP can cost between 400 and 2,000 euros
• Faster validation: You can launch in 4-8 weeks, not 6 months
• Niche = less competition: Instead of competing with Notion, you compete in a market where nobody has solved the problem well
• Profitable sooner: With 50 users at 20 euros/month you already have 1,000 euros in recurring revenue
• Low risk: If it doesn't work, you've invested little. You pivot and try something else

How to validate your idea before writing a single line of code:

1. Identify a problem that you or people close to you have
2. Search Reddit, Twitter/X, and forums to see if others are complaining about the same thing
3. Create a landing page describing the solution and an interest form
4. If 50 people sign up in two weeks, you have something. If not, try another idea
5. Talk to 10 of those people. Ask how much they'd pay

Validation is the step that 90% of founders skip. And that's exactly why 90% fail.

The Tech Stack for Building a SaaS in 2026

This is where most guides tell you to "pick the technology you know best." We're going to be more specific, because in SaaS development the stack matters and directly affects cost, development speed, and ability to scale.

Frontend: Next.js + React + TypeScript

Next.js is the React framework used by Vercel, Notion, and thousands of startups. It gives you Server Components (server-side rendering, better SEO), App Router (organized routes), and TypeScript for typed code with fewer bugs. It's the market standard in 2026.

Backend and database: Supabase (PostgreSQL)

Supabase is an open-source alternative to Firebase built on PostgreSQL. It gives you a database, authentication, storage, and edge functions. All in one. It has a generous free tier to get started and scales well. For a SaaS, Supabase cuts weeks of development on user management, permissions, and data.

Authentication: Supabase Auth

Registration, login, user roles, magic links, OAuth (Google, GitHub). All included in Supabase, without having to build an auth system from scratch. A step that used to take weeks now takes hours.

Payments and subscriptions: Stripe

Stripe is the standard for online payments in SaaS. Recurring subscriptions, free trials, billing, plan management. The integration with Next.js is straightforward. It charges 1.5% + 0.25 euros per transaction in Europe.

Deployment: Vercel

Automatic deploys from Git, preview URLs for every pull request, global CDN, auto-scaling. Vercel has a free tier that's perfect for getting started and scales without you touching infrastructure.

AI-assisted development

In 2026, building a SaaS without AI tools is like writing code without autocomplete. Tools like Claude Code, Cursor, or Vercel's v0 speed up development by 30% to 50%. They don't replace you as a developer. They multiply you. If you want to understand how different AIs compare for development work, read our Claude vs ChatGPT comparison.

Why this stack and not another? Because it's the one we use every day at LetBrand to build digital products. Next.js + Supabase + Stripe + Vercel gives you a functional, scalable, and maintainable SaaS in the least time and at the lowest cost possible. It's not the only valid stack. But it's the one with the best value-for-money ratio in 2026 for SMBs and entrepreneurs.

Legitimate alternatives: Laravel (PHP) if you come from that ecosystem, Django (Python) if you need heavy data processing, Ruby on Rails if you prioritize prototyping speed. All are solid. But none has the deployment ecosystem, free hosting, and developer experience that Next.js + Vercel offers in 2026, especially if you're building your first SaaS startup.

How Much It Costs to Build a SaaS in 2026

The ranges you'll find online about how much it costs to build a SaaS are absurd: "from $5,000 to $500,000." That doesn't help anyone. Let's get specific with the real costs of SaaS development.

Micro SaaS MVP: 400-3,000 euros. The essentials: landing page, auth, core functionality, Stripe payments. 4-8 weeks of development.

Full-featured SaaS: 5,000-15,000 euros. Auth + roles + dashboard + admin panel + payments + notifications + onboarding. 8-16 weeks.

Enterprise SaaS: 15,000-50,000+ euros. Multi-tenancy, APIs, third-party integrations, advanced analytics, compliance. 4-12 months.

Monthly infrastructure costs (to get started):

• Vercel: Free (hobby tier) or 20 euros/month (Pro)
• Supabase: Free (up to 50,000 rows) or 25 euros/month (Pro)
• Stripe: Transaction fees only (no fixed cost)
• Domain: ~10 euros/year
• Transactional email (Resend): Free up to 3,000 emails/month
• Total to get started: 0-50 euros/month

According to Cleveroad's analysis, internationally a SaaS MVP costs between $5,000 and $15,000 (50-100 hours of development). With AI tools, that time drops by 30-40%, bringing the cost down to $3,000-$8,000. With more competitive development costs, the numbers are even more favorable.

At LetBrand we build SaaS MVPs starting from 400 euros. Check our plans and pricing to see what each tier includes.

Marta, founder of a medical appointment management startup, learned the lesson the hard way. "I hired a large agency that quoted me 48,000 euros for the first version. It took 7 months. When we launched, I discovered the market wanted something different from what we'd built." After that failure, she rebuilt the product as a micro SaaS with a small team. Cost: 2,500 euros. Time: 6 weeks. "The difference was that this time I launched fast, talked to users from day one, and only built what they asked for."

The Steps to Build Your SaaS from Scratch

Step 1: Validate the idea (week 1-2)

Don't build anything yet. Talk to people who have the problem you want to solve. If 10 people tell you "I'd pay for this" and at least 3 of them specify how much they'd pay, you have a strong signal. If not, find another problem.

Step 2: Define your MVP (week 2-3)

The MVP isn't "the product with fewer features." It's the smallest version that solves the core problem and lets you charge for it. If your SaaS manages reservations, the MVP is: login + calendar + create reservation + payment. Nothing more. No analytics, no mobile app, no integrations.

Step 3: Build the MVP (week 3-8)

With the stack we've described (Next.js + Supabase + Stripe + Vercel), SaaS development of a functional MVP takes 4-8 weeks. It's the fastest way to build a real digital product and get it into users' hands. Use AI tools to accelerate. Don't chase perfection. Build something that works and that you can put in front of real users.

Step 4: Launch and charge from day one

Charging is the only validation that matters. If people don't pay, you don't have a business. You have a hobby. Launch with a price, even if it's low. 10 euros/month is better than free, because the act of paying filters for users who truly have the problem.

Step 5: Iterate based on data

Once you have paying users, listen. Look at which features they use, which they ignore, what they request. Build what they ask for, not what you think they need. The metrics that matter: churn (how many leave), MRR (monthly recurring revenue), NPS (satisfaction).

Step 6: Scale what works

When you have product-market fit (users who pay, don't leave, and recommend you), it's time to invest in growth. SEO (you need people to find you on Google, and this is where understanding how SEO works today makes the difference), content marketing, and maybe some AI built into the product. If you want ideas on how to integrate AI agents into your SaaS, we have a guide for that.!Diagram of the steps to build a SaaS from scratch with timeline

The SaaS Business Model: Pricing and Key Metrics

Your SaaS pricing can make or break the business. These are the three main strategies:

Freemium: Limited free version + paid plans. Works if your product has a network effect (more users = more value) or if the marginal cost of a free user is close to zero. Examples: Slack, Notion, Canva.

Free trial: Full access for 7-14 days, then payment. Works better than freemium for B2B SaaS where the value is demonstrated through real usage. Fewer free users who never pay.

Direct payment: No free version. The user pays or doesn't use it. Works when the problem you solve is so clear and urgent that you don't need to convince anyone. Ideal for niche micro SaaS.

The 10x rule for pricing: Your product should save the user at least 10 times what it costs them. If your SaaS saves them 500 euros/month in time, charge 50 euros/month. Not 5.

Metrics you should track from day one:

• MRR (Monthly Recurring Revenue): Monthly recurring income. The most important metric.
• Churn: Percentage of users who cancel each month. If it's above 5% monthly, you have a problem.
• LTV (Lifetime Value): How much a customer pays throughout their entire relationship with you.
• CAC (Customer Acquisition Cost): How much it costs to acquire a new customer. LTV should be at least 3x CAC.

Diego, co-founder of an inventory management SaaS for restaurants, launched at a price of 15 euros/month. "We thought being cheap would get us more customers." After 4 months with 80 users and an MRR of 1,200 euros, they ran a survey: most users said they would have paid 40-50 euros/month. They raised the price to 45 euros/month for new customers. Churn didn't change. Their MRR tripled in 3 months.

What Nobody Tells You About Building a SaaS

Most fail. Not because of the product. Because of lack of distribution. Building is the easy part. Getting people to find it, try it, and pay is the hard part. If you don't have a customer acquisition strategy (SEO, content, partnerships, cold outreach), the best product in the world sits on your server with no users.

Customer support takes more than development. When you have 50 paying users, each one expects responses. Bugs, questions, feature requests. Be prepared to spend as much time on support as on development, especially in the beginning.

Marketing is harder than building the product. You can build a SaaS in 6 weeks. Getting your first 100 paying customers can take 6 months. Invest in marketing from day one. Don't wait until the product is "perfect."

Founder loneliness is real. If you build alone, you're going to have days when everything feels pointless. That's normal. Find communities (Indie Hackers, X/Twitter SaaS, micro SaaS communities on Discord). The support of others on the same path is worth more than any course.

When to look for a technical partner: If you can't code, you need someone who can. Not a freelancer for a one-off project. A partner or a studio that understands your long-term vision. The difference between a freelancer who disappears and a team that walks with you can be the difference between your SaaS startup succeeding or failing.

Your SaaS Starts with a Decision

Let's recap the essentials:

• A SaaS is cloud software with a recurring subscription. The most scalable business model there is.
• Micro SaaS is the smartest way to start: low cost, fast validation, minimal risk.
• The recommended stack in 2026 is Next.js + Supabase + Stripe + Vercel, with AI-assisted development.
• A SaaS MVP can cost as little as 400 euros and be ready in 4-8 weeks.
• Charge from day one. The only validation that matters is someone paying.
• The ones who survive aren't those with the most money. They're the ones who validate fastest and spend the least.

The barrier to entry for building a SaaS has never been lower. The stack is free to start, AI tools multiply your productivity, and a focused micro SaaS can generate real revenue with fewer than 100 users.

What you're missing isn't technology. It's taking the leap.

Want to build a SaaS and need a technical team to make it happen? Tell us about your project. We'll tell you if it makes sense, what it would cost, and how long it would take. No pitch, no commitment. Just technical honesty.