SaaS & MVP Development

Launch your SaaS on solid foundations

No more choosing between speed and quality. We build scalable MVPs designed to delight your first users and reassure your investors.

Why 80% of SaaS projects fail technically?

The 'Black Box' Effect

Developers who don't understand your business vision and deliver off-target.

Spaghetti Code

A hastily cobbled MVP that must be completely thrown away once you reach 100 users.

Perpetual Delays

A 3-month roadmap that turns into 1 year. Meanwhile, your competitors move forward.

Lack of Scalability

An application that crashes as soon as traffic increases. Goodbye growth.

The Aetherio Method: Your Fractional CTO

The tech & product partner a startup can't yet afford internally

Product Vision & MVP

We help you decide: which features are vital for V1? We eliminate the superfluous to ship fast.

Product Prioritization (MLP, not MVP)
12-week max roadmap for V1
Focus on acquisition & retention
Business hypothesis validation

Scalable Architecture from Day 1

No shortcuts. We use modern, proven stacks. Your V1 can handle your future growth.

Multi-tenant ready
API-first architecture
Microservices when needed
From 10 to 10,000 users without rebuild

AI & Innovation

Native AI integration to give your product an immediate competitive 'Wow effect'.

GPT, Claude, Mistral integration
Intelligent workflows
Personalized AI
Market differentiation

Transparent Collaboration

Direct access to devs, weekly demos. You drive the project with us, hand in hand.

Live weekly demos
Direct Slack/Discord with devs
1-2 week sprints (your choice)
Zero tunnel vision

Built to sell (or to last)

We understand SaaS metrics (Churn, MRR, LTV, CAC). We design the user journey (UX) to maximize conversion and user retention. Your code is documented, tested, and auditable: a valuable asset for future fundraising or exit.

Native SaaS metrics

Churn, MRR, Activation dashboards integrated from V1

Optimized onboarding

User journey designed to convert and retain

Auditable code

Technical documentation for due diligence

Scale-ready

Validated architecture for exponential growth

Custom SaaS development: how it actually works

A custom SaaS is not a website with a payment form. It is a multi-customer product, billed on a recurring basis, that has to stay operable when account numbers grow a hundredfold.

Multi-tenancy: the decision that shapes everything else

The first architecture question on a SaaS is not the framework, it is how your customers' data coexists. A shared database with a tenant column is cheap and quick to ship. A database per customer isolates completely but complicates every migration. A schema per customer sits in between.

This choice is hard to reverse once you have customers in production. We settle it in Sprint 0, based on your real constraints: regulated sector or not, reversibility commitments, expected volume, isolation requirements from your future enterprise accounts.

The pieces every SaaS ends up having to build

A subscription product needs a foundation that classic custom projects do not: organisation and invitation management, roles and permissions, authentication with SSO for enterprise customers, recurring billing with plan changes and failed payments, usage quotas and limits, activity logs.

These pieces take a significant share of a first launch budget, and none of them differentiate your product. We assemble them from proven components, Stripe for billing, an identity provider for SSO, rather than rewriting them. The budget goes to what creates your value.

Designing for measurement, from version one

A SaaS is steered with numbers: how many created accounts reach their first useful action, which features are actually used, when a customer disengages before cancelling.

This data is not easy to add after the fact. We instrument the key journeys from the first sprint, so you have real signals when prioritisation decisions arrive. It is also what makes a case credible in front of investors or an acquirer.

Custom or no-code: our honest position

To validate a hunch with twenty users, a no-code tool is often faster and far cheaper. We say so when that is the case, even if it means turning down the project.

Custom development becomes the right call when the business logic is unusual, when you need to integrate with customer systems, when per-seat platform costs become prohibitive as you grow, or when the code needs to be a valuable asset. We regularly take over products that started in no-code and hit that ceiling.

They launched with us

From idea to production, with real traction

Fideneo

B2B SaaSBusiness Management

12 weeks

MVP launched in 12 weeks. Scalable multi-tenant architecture. From 0 to production without technical debt.

Multi-tenant architecture

SSO authentication

Documented REST API

Automated tests

View all our SaaS achievements

Why we're not a traditional agency

No opaque subcontracting

You know exactly who codes your project. Direct access to developers, no telephone game.

Technical excellence

We're obsessed with code quality (Clean Code, tests, documentation). This is your future peace of mind guarantee.

Human-centered

Technology is just a tool. Our goal is to make life easier for humans who use it: your users, your team, you.

B2B SaaS development: what changes when your customers are companies

Selling to companies puts constraints on the product that do not exist in B2C, and they almost always surface at the worst moment: during the sales cycle.

The requirements that block a signature

A first enterprise account arrives with a list: single sign-on through their directory, fine-grained role management, audit logs, full data export, hosting in the European Union, a reversibility commitment. None of it shows in a product demo, and each item can delay a signature by months.

We put them on the roadmap as soon as a move toward B2B is on the table, rather than discovering them in a security questionnaire sent by the prospect's procurement team.

Billing: the reality of enterprise contracts

In B2C, a card subscription is enough. In B2B, customers ask for annual payment on invoice, purchase orders, intra-EU VAT, negotiated pricing, extended trials and sometimes billing per active user.

That complexity is structural, not cosmetic. We design the billing model alongside the data model, because reworking one without the other always costs more.

Integrations: your product lives in an ecosystem

B2B software that talks to nothing stays one more tool to open in a tab. Your customers expect it to connect to what they already run: their CRM, their billing tool, their team messaging, their ERP.

We plan a documented API and webhooks from the design stage. That is what lets your customers build their own automations, and it is often what makes them stay.

SaaS development agency in Lyon

We are based in Villeurbanne, in the Lyon metropolitan area, and we work with software vendors and founders across the Auvergne-Rhône-Alpes region.

Three SaaS products in production, not mockups

Kabineo, Fideneo and Belho Xper run with real users and real operational constraints. That is the difference between an agency that delivers a project and a team that has already lived through the problems that appear after eighteen months: data migrations on a live database, infrastructure bills that drift, the feature nobody uses that has to be removed cleanly.

That experience changes the decisions we make at the start, usually toward simplicity.

One technical counterpart, not a chain of them

On a SaaS project, most bad decisions come from a communication gap between product vision and technical execution. We remove that gap: you talk directly to the people designing the architecture and writing the code.

For non-technical founders we act as fractional CTO: architecture trade-offs, third-party vendor selection, hiring your first developers, preparing technical due diligence.

You own the code, entirely

Git repository in your name, architecture documentation, deployment procedures, access to all infrastructure. No proprietary component that would keep you dependent on us.

Our clients often end up bringing their engineering in house. We consider that a success, and we prepare the handover rather than complicating it.

Technologies used

Vue.js Nuxt.js NestJS TypeScript IA Générative

They trusted us

Founders and business owners who had a project, a need, a deadline. Here's what they have to say.

"Disponibilité, réactivité et implication. Valentin est professionnel et pédagogue."

Alban B.

CEO Belho Xper

"Il allie une expertise technique pointue à une solide vision business."

Charley A.

Co-fondateur Avnear

"Nous avons travaillé ensemble sur la conception d'une automatisation IA pour un E-commerce. Le suivi a été régulier, clair et efficace. Les délais respectés et le résultat impressionnant."

Chihab A.

CEO E-commerce

"Valentin a su être à l'écoute de mes besoins et les retranscrires dans une application de gestion de clientèle. Les résultats ont été plus que satisfaisants et de haute qualité."

Sandrine V.

Gérante Sandrin's Nail

"Une entreprise qui sait s'adapter parfaitement au besoin client."

Stanislas M.

Commercial

"Le site est clair, rapide, et nous permet de mettre en avant nos services de manière professionnelle. Nette augmentation des demandes."

Christophe R.

PDG Ravi Groupe

See all client reviews

Frequently asked questions

What's the difference between MVP and MLP?

The MVP (Minimum Viable Product) is the minimum viable product. The MLP (Minimum Lovable Product) goes further: it's the minimum product that your users will love. We favor MLP because it maximizes your chances of adoption and retention from V1.

How long to launch a SaaS?

A well-framed MLP launches in 6 to 12 weeks. A complete SaaS with payments, multi-tenant, and third-party integrations takes 3 to 6 months. It all depends on the functional scope we validate together during Sprint 0.

What happens if I want to pivot mid-way?

It's normal for a startup! Our short sprints (1-2 weeks) and modular architecture allow quick pivots without throwing everything away. We adjust the roadmap together at each sprint.

Can you help me raise funds?

We're not an investment fund, but we prepare your technical due diligence: auditable code, documented architecture, SaaS metrics in place. We can also be present during pitches to reassure on the tech side.

Can I take the code and continue with my internal team?

Absolutely! The source code belongs to you 100%. We document everything (architecture, README, conventions) to facilitate handover. We can also train your technical team during the transition.

What happens after launch?

We stay with you in support & evolution mode. You choose: hourly packages, recurring sprints, or fractional CTO mode to drive long-term product growth.

How much does custom SaaS development cost?

A first usable product starts at €15,000 for 6 to 12 weeks. A complete B2B SaaS, with organisation management, roles, SSO and subscription billing, sits between €30,000 and €80,000 depending on scope. The gap rarely comes from visible features: it comes from how demanding you are on data isolation, compliance and third-party integrations. We quote precisely after Sprint 0, with a committed budget.

Should we go multi-tenant from the start?

Yes, in almost every case. Adding a tenant concept to an application that has none means touching every query, every access check and every screen. It is a multi-week project that lands at the worst possible time, once you already have users. The real question is not whether you go multi-tenant, but which isolation level to pick between shared database, schema per customer and dedicated database.

Can we build a SaaS without technical skills?

Yes, that is the profile of most of our founder clients. What we need from you is not engineering, it is a sharp understanding of the problem you solve and access to users for validation. We handle architecture, technical trade-offs and infrastructure choices, and we explain them in plain language with their consequences on budget and timeline.

How do you handle subscription billing?

With Stripe in the vast majority of cases: subscriptions, free trials, plan changes with proration, dunning on failed payments, compliant invoices. We wire the webhooks so account state in your application follows payment state in real time. For enterprise customers who require annual payment on invoice, we add a parallel manual billing path.