SaaS MVP Tech Stack: A Guide for EU Founders

The best SaaS MVP tech stack is the one the people who will maintain it already know. If you have no strong preference, my default is TypeScript with Next.js, PostgreSQL, a proven auth library or service, Stripe or Mollie for payments, and one app server plus a managed database in an EU region. Rails or Django are equally good choices if your team knows them. The framework matters less than three decisions that are hard to undo later: how you separate tenants, where personal data lives, and how you bill.

Below: that default, a comparison of three common options, and a checklist of decisions to make first.

Rule one: pick a SaaS MVP tech stack the maintainers know

MVP code usually stays in production long after launch. So the main question is not “which stack is fastest?” It is “who can work on this in two years?”

Hiring pool is part of that answer. In the Stack Overflow Developer Survey 2025, 55.6% of respondents said they used PostgreSQL and 43.6% used TypeScript. Among web frameworks, 20.8% used Next.js, 12.6% Django and 5.9% Ruby on Rails. A survey of its own readers is not the job market. It does show that you will not struggle to find people who know Postgres or TypeScript.

A smaller share does not make Rails a bad choice. It means you should check your local hiring market before you commit.

Next.js vs Rails vs Django for a SaaS MVP

All three can carry a SaaS product well past the MVP stage. The differences are in what you get for free and what you assemble yourself.

• Rails calls itself “omakase” in its doctrine: one curated set of tools that work together. Rails 8 added an authentication generator, database-backed jobs, cache and WebSocket adapters, and Kamal 2 for deployment to your own server. For an MVP that removes several decisions.
• The Django admin saves weeks on internal tools. Its own documentation limits it to an organization’s internal management tool, not your customer-facing front end. Use it for support and operations screens, and nothing else.
• Next.js gives you the most freedom and the most choices. That is a risk for an MVP. If you choose it, also choose your auth, ORM, queue and email libraries on day one and write them down, so the team does not debate them each sprint.

My default is TypeScript and Next.js because one language across the stack makes a small team more flexible. If your co-founder writes Rails or Django every day, use that instead. That is a better reason than anything in this article.

Database: PostgreSQL, and decide multi-tenancy now

Use PostgreSQL unless you have a specific reason not to. It is open source under a permissive licence, and it is the database most engineers already know (see the survey numbers above). One database is easier to back up, secure and reason about than two.

The decision that matters more than the database is tenancy. A B2B SaaS stores data for many customer organizations. You can separate them in three ways: a tenant_id column on every table, a schema per tenant, or a database per tenant. For an MVP, I recommend the tenant_id column. It is the simplest to run and to migrate.

The risk is a query that forgets the filter and shows one customer’s data to another. Postgres has row security policies that let the database enforce the filter. Note one detail from the documentation: table owners bypass these policies by default. If your app connects as the table owner, the policies do nothing unless you use FORCE ROW LEVEL SECURITY or connect as a separate role. Test it with two tenants before launch.

Adding tenancy to a single-tenant MVP later means touching every table and every query. Decide it before the first table exists.

Authentication: do not write password storage yourself

Sign-in is easy to get wrong and users only notice it when it fails. Do not write it from scratch.

If you store passwords, use your framework’s built-in auth or a well-maintained library. The OWASP Password Storage Cheat Sheet recommends Argon2id first, then scrypt, with bcrypt for legacy systems. Check that whatever you use follows it.

The other route is a managed auth service. The trade-offs:

• Managed service: faster to add single sign-on, multi-factor auth and social login. But your user records live with a vendor, the cost grows with active users, and moving away later is work. Check the hosting region and sign a data processing agreement (see below).
• Framework auth: your users stay in your own database and there is no per-user cost. You build the screens and own the security updates.

For a B2B MVP with email sign-in and one or two roles, framework auth is enough. If your first customers are larger companies that require single sign-on, a managed service pays for itself quickly.

Payments for EU customers: Stripe or Mollie

Both Stripe and Mollie are common choices for European SaaS. Pick based on the payment methods your customers use and how you want to handle subscriptions.

If you sell to Dutch customers, check iDEAL. Stripe’s documentation asks merchants to rebrand iDEAL to “iDEAL | Wero” in the first quarter of 2026 and to switch to Wero during 2026 and 2027. Plan for that change in your checkout. iDEAL is a one-off payment. For subscriptions, both providers let the first iDEAL payment set up a SEPA Direct Debit mandate for later charges. See Stripe’s iDEAL page and Mollie’s recurring payments guide.

VAT is the part founders forget. If you sell to consumers in other EU countries, the EU’s One-Stop Shop lets you declare that VAT in one return. B2B sales follow different rules. Ask your accountant which applies before you design the checkout, not after. If you would rather not handle VAT at all, a merchant-of-record provider resells your product and takes on that work. Compare its fees with the time VAT would cost you.

Hosting and GDPR

Your SaaS processes personal data for your customers, so the GDPR shapes your hosting choices.

1. Every vendor that processes personal data for you (hosting, database, email, auth, error tracking, analytics) needs a contract. Article 28(3) requires one. Most vendors offer a standard data processing agreement. Collect them in one folder.
2. Transfers outside the EU need a legal basis under Article 44 and the rest of Chapter V. For US companies, the European Commission adopted an adequacy decision on 10 July 2023 that covers companies taking part in the EU-US Data Privacy Framework. Check that each US vendor takes part.
3. Choose EU regions for your database and app servers. B2B customers often ask about this in security questionnaires before they sign.
4. Keep a list of sub-processors. You will need it for your privacy notice and for customer questions.

On architecture: one app server, one managed Postgres database with automatic backups, and object storage for files. Containerize the app so you can move hosts. That is enough for most MVPs.

What to leave out of v1

• Microservices. The Rails doctrine argues for integrated systems over distributed ones early on. I agree. One codebase is easier to change while you learn.
• Kubernetes. A managed container service or a plain VM is easier to run for a small team.
• A second database. Add Redis, a search engine or a vector store only when Postgres cannot do the job.
• A native mobile app. A responsive web app covers most B2B use. See what an MVP should and should not include.
• Custom billing. Use the payment provider’s hosted checkout and billing portal until you have paying customers.

If you have not yet decided what goes into v1, start with how to scope an MVP. The stack follows the scope, not the other way round.

Decisions that are hard to change later

Make these before you start building.

• Who maintains the code in two years, and which stack they know
• Tenancy model, and whether the database enforces it
• Where user accounts live (own database or auth vendor)
• Payment provider, payment methods per country, and who handles VAT
• Hosting region for the database, app servers, files and backups
• Data processing agreement signed with every vendor that processes personal data
• Which personal data you store, and for how long
• Code, domain and cloud accounts owned by your company, not by an agency
• A tested restore from backup

FAQ

What is the best tech stack for a SaaS MVP?

There is no single best one. A good default is the stack your team already knows, on PostgreSQL, with proven auth, a payment provider’s hosted billing and EU hosting. If you have no preference, TypeScript with Next.js is my default, as explained above.

Should I use no-code for a SaaS MVP?

It can work for a smoke test or an internal tool. For a multi-tenant B2B product that stores customer data, check data export, region and access control first. Plan for a rebuild if the test succeeds.

Can I change the stack later?

You can change the front end, the host and most libraries later. The data model, the tenancy approach and the language of the core code are the expensive ones to change.

Next step

If you want a second opinion on your stack before you start, our technology consulting includes stack and architecture reviews. If you are ready to build, see how our SaaS development works. Engagements are fixed-scope after a short discovery sprint. Or book a free 30-minute call and bring your shortlist.