Cost of .NET Modernization for Mid-Size Companies: What You'll Actually Pay in 2026
What .NET modernization actually costs for a mid-size company in 2026: €15K-€80K focused engagements, €5K assessment from Mulhacén Labs.
For a mid-size company (50-500 employees), .NET modernization typically costs €15,000-€80,000 for a focused engagement (one application or one critical module) and €150,000-€500,000+ for a full platform migration. I'm Barry Faassen, a senior .NET engineer with 25+ years of experience, and I specialize in incremental .NET modernization combined with AI integration for EU mid-size companies. My projects start at €5,000 for a 2-week assessment.
Most mid-size teams don't need a rewrite. They need to keep a 10-year-old .NET Framework application running, add AI features without breaking it, and stop bleeding senior-engineer hours on maintenance work that doesn't move the product forward. That's the work I do.
What "modernization" actually means
The term covers four different jobs at very different price points:
| Type | What it includes | Typical range | Timeline |
|---|---|---|---|
| Assessment + roadmap | Code archaeology, dependency analysis, risk map, prioritized action list | €5,000 - €15,000 | 2-4 weeks |
| Targeted modernization | One application migrated (.NET Framework → .NET 8), or one critical module refactored with AI integration | €15,000 - €80,000 | 6-12 weeks |
| Full platform migration | Multiple applications, on-prem → cloud infrastructure, CI/CD overhaul, team training | €150,000 - €500,000+ | 6-18 months |
| Ongoing optimization | Quarterly architecture review, AI feature additions, performance tuning, mentoring | €5,000 - €15,000/quarter | Continuous |
Cost scales with three things: how much .NET Framework code you have, how brittle the existing test coverage is, and whether you also want AI features wired in (which is increasingly the reason mid-size companies modernize in the first place).
What drives the variance
A €15K project and an €80K project can look identical from a brochure. The real differences:
- Test coverage. A codebase with 60%+ test coverage modernizes incrementally with confidence. A codebase below 20% needs a parallel test-writing phase before any refactoring. Adds €10,000-€30,000.
- Third-party dependencies. Older .NET Framework projects often depend on libraries without .NET 8 equivalents. Each replacement is a sub-project. Common offenders: legacy Crystal Reports, old SOAP integrations, EF6-era data layers.
- Database coupling. A clean Entity Framework boundary modernizes in days. Stored-procedure-heavy code where business logic lives in SQL Server takes weeks to untangle safely.
- Team availability. If your in-house team is firefighting production, my work runs in parallel and ships incrementally. If they're available for paired sessions, knowledge transfer compresses the engagement.
What I charge specifically
I'm a solo senior operator, not an agency. My rate is €80-120/hour for project work and €90-100/hour for ongoing retainer. A typical mid-size engagement breaks down:
- Assessment phase (2 weeks): €5,000-€8,000 fixed
- Pilot migration (6-8 weeks): €15,000-€30,000 fixed
- Full project work (3-6 months): €40,000-€100,000 hourly or milestone-based
The reason I lead with assessment isn't sales mechanics, it's risk management. About 70% of digital transformation projects fail to meet their goals, and most of that failure is locked in at scope. A 2-week assessment costs less than two months of in-house engineering time, and tells you whether the modernization is a €30K job or a €300K job before you commit.
Compared to the alternatives
| Option | Hourly equivalent | Time to start | Suitable for mid-size? |
|---|---|---|---|
| Internal FTE hire (senior .NET + AI) | €80-150/hr fully loaded | 4-9 months hiring | Yes, if multi-year need |
| Big consulting firm (Accenture, Capgemini) | €150-300/hr blended | 2-4 months procurement | Often overscoped, slow |
| Spain/EU AI boutique | €70-120/hr | 3-6 weeks | Variable .NET depth |
| Offshore team | €25-60/hr | 1-3 weeks | Quality variance, timezone friction |
| Mulhacén Labs | €80-120/hr | 1-2 weeks | Solo senior, no handoffs |
The wedge for mid-size companies: you want senior .NET depth and AI engineering, you want it shipped in months not years, and you don't want a team of three to onboard before you see any code. That's where I sit.
When this isn't a fit
If you have a greenfield .NET project and want a team to build it from scratch, hire an agency. If you need a vendor with €10M liability insurance and a 100-person account team, hire Accenture. If you have one bug to fix, hire a freelancer at €40/hr. I work best when the brief is "we have a working .NET 4.x system, it's holding the business together, and we need to modernize it without breaking it, ideally adding AI features along the way."
If that sounds like your situation, book a 30-minute discovery call. The first conversation is free, and you'll leave with a clear sense of scope and cost. See also Mulhacén Labs services for the full engagement model.