How much does an MVP or custom application cost?
It depends on the scope. An MVP starts around €5,000, a full business application between €10,000 and €30,000. We define the budget together from the first call to avoid surprises.
From idea to the application that generates revenue
Building an MVP, SaaS or business app? I handle the entire technical side. Product strategy, architecture, code, production deployment.
Your technical partner, not just a contractor
I'm Valentin Muller, Full Stack developer and entrepreneur based in Villeurbanne. I build my own products and startups on the side, which allows me to understand your founder challenges from the inside.
Before writing a single line of code, I take the time to understand your business, your market and your constraints. That's how you build products that last, not prototypes you throw away after 3 months.
I use artificial intelligence daily to design, develop and manage my projects. Combined with years of experience and staying on top of the latest technologies, it allows me to go faster and further than what a solo developer could do just 2 years ago.
Whether it's a business application, a SaaS or a website, I invest for the long run. My goal: that your product generates value well beyond launch day.
Services
What I build for my clients
Every project starts with a real business problem . I build technical solutions that serve your business, not showcases gathering dust. From SaaS products to internal tools, everything is built to last and scale.
Real projects, measurable results
Every project shown here solved a real business problem. SaaS applications, business tools, high-performance websites. Here's what I've built for my clients.
Discover
Belho Xper App
Web Application / SaaSMulti-tenant SaaS application for accounting firms: client management, automated tax tasks and real-time planning.
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Fideneo
Web Application / SaaSFideneo is an all-in-one cockpit designed to simplify and automate beauty salon management.
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BELHO XPER
Accounting FirmA custom website redesign to reposition Belho Xper as a modern, reliable accounting firm with high added value.
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MAISON & MATIERES
Interior DesignA premium website with interactive 3D experience and animations for high-end interior decoration specialists.
What changes when you work with me
You can choose an agency, a freelancer or a no-code solution. Here's what you get with Aetherio.
Premium
Aetherio
I understand your business
I don't code blindly. I take the time to understand your market, your users and your goals before touching code.
Code, not templates
Everything is custom-built. No WordPress, no no-code. Your product belongs to you, with no dependency on third-party tools.
Built to convert
SEO, performance, user journey. Every technical decision is made so your product brings in customers, not just visitors.
Fast delivery, lasting quality
You see results in weeks, not 6 months. And the code is built to evolve with your business.
One point of contact, from A to Z
No project manager, no salesperson. You talk directly to the person who designs and codes your product.
Standard
Standard solutions
Standardized brief
A questionnaire, a quote, and off we go. Little time spent understanding your real challenges.
Templates and plugins
An adapted theme, a few plugins. Quick to deliver, but you look like everyone else.
Conversion as an afterthought
The site is live, but nobody thought about how it's going to generate business.
Extended timelines
Multiple contacts, back and forth, weeks without news. The project drags on.
Technical dependency
You can't change anything without going back to the agency. The code doesn't really belong to you.
They trusted me
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."
A
Alban B.
CEO Belho Xper
"Il allie une expertise technique pointue à une solide vision business."
C
Charley A.
Co-fondateur Avnear
"La communication a toujours été fluide et les délais respectés, ce qui est rare et très appréciable."
C
Chihab A.
CEO E-commerce
"Valentin a su être à l'écoute de mes attentes et de mes besoins. Les résultats ont été plus que satisfaisants."
S
Sandrine V.
Gérante Sandrin's Nail
"Une entreprise qui sait s'adapter parfaitement au besoin client."
S
Stanislas M.
Commercial
"Depuis la mise en ligne, nous avons remarqué une nette augmentation des appels et des demandes de renseignements."
C
Christophe R.
PDG Ravi Groupe
How we work together
A simple and transparent process. You know where we stand at every step.
1
We talk
A first conversation to understand your project, your market and your constraints. No lengthy brief, a direct conversation.
2
Scoping and strategy
We define the scope, priorities and timeline together. You know exactly what will be delivered and when.
3
Mockups and validation
I design your product mockups. You validate before I touch code. No bad surprises.
4
Iterative development
I develop in functional blocks. You test as we go, we adjust continuously. No 3-month tunnel with no news.
5
Production deployment
Deployment, SEO, monitoring. Your product is live, fast and indexed.
6
Support and evolution
I stay available after launch. Fixes, new features, maintenance. Your product keeps evolving.
My tech stack
The technologies I use daily to build performant and scalable products.
Vue.js
Framework frontend réactif
Nuxt
Full-stack Vue, SSR & SEO
TypeScript
Typage strict, code robuste
NestJS
API backend structurée
Tailwind CSS
Styling utilitaire, rapide
Astro
Sites statiques ultra-performants
Three.js
Expériences 3D immersives
Supabase
Auth, database, storage
PostgreSQL
Base de données relationnelle
Redis
Cache & temps réel
n8n
Automatisation de workflows
Figma
Design UI/UX & prototypage
Vercel AI SDK
Intégration LLM en production
Claude Code
Développement assisté par IA
Cursor
IDE augmenté par IA
Your questions, my answers
The questions founders and business owners ask me most before getting started.
How soon can my product be live?
An MVP can be in production in 4 to 8 weeks. A full business application takes 2 to 4 months depending on complexity. You get access to intermediate versions throughout development.
Why work with a freelancer rather than an agency?
No middleman, no salesperson. You talk directly to the person who codes your product. It's faster, more transparent, and often cheaper than an agency at equal quality.
Can you support me throughout the product's life?
Yes. I don't disappear after delivery. Maintenance, new features, scaling, I remain your technical point of contact for the long term.
How does payment work?
40% upfront, 60% on delivery. For longer projects, we can split into monthly milestones. Payment by bank transfer.
What if I just have an idea, no specs yet?
That's the case for most of my clients. We start from your idea and build the scope together. That's precisely my role: turning a vision into a concrete technical action plan.
What if my project is too big for one freelancer?
I rely on a network of expert freelancers in their fields: design, marketing, sales, development. Whatever the ambition level of your project, we build the right team. You keep one point of contact, me, and I coordinate the rest.
Have a project? Let's talk.
Free first call, no commitment. Let's see together if we can work on your project.
Discover my resources
Complete Web Application Development Guide 2026: Methodologies, AI & Best Practices
19/01/2026
How to Land Your First SaaS Customers: Strategies That Truly Work
05/02/2026
Offshore Development: The Real Savings and the Pitfalls No One Tells You About in 2025
04/30/2026
Mobile App for Your Business: Is It Really Worth Building One?
04/29/2026
Employee Management App: Scheduling, Time Tracking & Leave Without Headaches for SMBs
04/28/2026
How to Build a Marketplace or Matching Platform: A 2025 Guide for Entrepreneurs
04/25/2026