The verdict in three sentences
Hiring in-house makes sense when the app is strategic, continuously evolving and core to your business; an agency wins when you want to ship fast, spread the risk and avoid recruitment costs. A senior developer costs 60,000 to 85,000 EUR fully loaded per year but takes 3 to 5 months to become operational; an agency at a 500-750 EUR day rate starts within one or two weeks. The best answer often combines both: agency to build, in-house to maintain.
The real cost of an in-house developer
A gross salary of 45,000 EUR becomes roughly 63,000 EUR fully loaded, plus workstation, licenses, training and management. Above all, you must hire: 3 to 5 months of lead time, 15 to 25 % of salary in agency fees if you outsource the search, and a churn risk within 18 months in a tight market.
| Item | In-house developer | Agency |
|---|---|---|
| Annual / mission cost | 60,000 to 85,000 EUR loaded | 500 to 750 EUR/day |
| Time before start | 3 to 5 months (hiring) | 1 to 2 weeks |
| Recruitment fees | 15 to 25 % of salary | 0 |
| Management overhead | High (tracking, HR) | Low (deliverables) |
| Downward flexibility | Low (permanent contract) | High (end mission) |
| Knowledge retention | Strong | Medium (contract it) |
| Fast scale-up | Difficult | Immediate (cross-functional team) |
Compared on a 6-month project
Take an MVP to ship in 6 months, roughly 110 useful person-days. At an agency with a 600 EUR day rate, that is 66,000 EUR, with no hiring or HR overhead. In-house, you must first recruit (3-5 months), then mobilize a profile at ~5,800 EUR loaded per month: the project does not start before the second half of the year.
| Scenario | Direct 6-month cost | Time to launch | Flexibility |
|---|---|---|---|
| 1 senior in-house dev | ~35,000 EUR (salary) + hiring | 3-5 months before start | Low |
| Agency (project team) | ~66,000 EUR | 1-2 weeks | High |
| Mix agency + 1 in-house | ~80,000 EUR | 2-3 weeks | Optimal |
The mix is often the most cost-effective: the agency brings speed and cross-functional skills, the in-house hire retains knowledge for maintenance.
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Mini case study
Sophie, CIO of an industrial mid-cap in Lyon, must ship a supplier portal in 5 months. Hiring two developers would cost ~130,000 EUR loaded per year and 4 months of recruitment, incompatible with the deadline. She hands the build to an agency for 72,000 EUR over 5 months, then hires a single developer for maintenance from month 6. Result: on-time delivery, 58,000 EUR saved in year 1 and an in-house team sized to the real need.
FAQ
What does a senior developer really cost in 2026? Budget 60,000 to 85,000 EUR fully loaded per year in France, excluding workstation and licenses. In a tight market, add 15 to 25 % recruitment fees and a 3-to-5-month lead time.
What day rate for a web app agency in 2026? The order of magnitude is 500 to 750 EUR per day for a cross-functional team (dev, design, project management). A 6-month MVP often represents 60,000 to 80,000 EUR.
Is an agency more expensive than in-house? Per day, yes; but with no hiring, HR overhead or under-utilization risk. For a one-off project under 12 months, an agency is almost always cheaper on a fully loaded basis.
How do I avoid agency dependence? Require code transfer, documentation and a handover phase. A mix of agency for the build and in-house for maintenance limits long-term risk.
Can I switch from agency to in-house later? Yes, that is the recommended pattern: the agency builds fast, then you hire a maintenance profile once the product is stable, saving the upfront recruitment months.
Let's scope your project. Tell us your scope, deadline and whether you target a one-off build or a lasting team; we will cost the in-house, agency and hybrid scenarios. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.
Mohamed Bah
Fondateur, Kolonell
Passionate about digital and entrepreneurship in Africa, Mohamed has been helping Sénégalese businesses with their digital transformation since 2020. Founder of Kolonell, he believes every SME deserves a professional and accessible online présence.
