The verdict in three sentences
For a company operating 140 furnished apartments let for 1 to 10 months to employees on assignment, a custom rental management app costs between 30,000 and 70,000 EUR excl. tax (about GBP 26,000 to 60,000) and ships in 4 months. Against off-the-shelf software billed at 5 to 12 EUR per unit per month, custom does not win on licence cost alone: it wins on occupancy rate, management time and control of mid-term lease rules. Above 100 units with specific processes, the gap widens in its favour from year three.
Why mid-term rentals slip through standard tools
Furnished lets of 1 to 10 months, in Paris as in London, sit between two worlds. Holiday rental software handles nights and platforms well, but leases, deposits and monthly receipts poorly. Traditional property management software handles 12-month tenancies, but not fast turnover or multi-channel calendars.
Yet in the same portfolio, short lets under a mobility lease (1 to 10 months in France, typically a company let or licence in London) coexist with standard furnished tenancies, and corporate clients book for their staff and want a single invoice.
| App feature | Concrete use | Share of budget (2026 order of magnitude) |
|---|---|---|
| Unified calendar and iCal / API sync | Airbnb, Booking, corporate sites, channel manager | 20% |
| Lease generation and e-signature | Mid-term lease, furnished lease, addenda, inventory | 15% |
| Rent and deposit collection | Direct debit, card, pre-authorisation, rent guarantee | 20% |
| Corporate client space | Bookings for employees, consolidated invoicing | 15% |
| Cleaning, check-in, maintenance | Contractor schedule, photos, tickets | 15% |
| Owner reporting and profitability | Revenue per unit, occupancy, payouts | 15% |
Off-the-shelf versus custom over 4 years
| Item over 4 years (140 units) | Off-the-shelf at 5 EUR/unit | Off-the-shelf at 12 EUR/unit | Custom |
|---|---|---|---|
| Licences or development | 33,600 EUR | 80,640 EUR | 50,000 EUR |
| Separate channel manager (3 EUR/unit/month) | 20,160 EUR | Included | Built in |
| Maintenance and hosting | Included | Included | 28,800 EUR (600 EUR/month) |
| Extra tools (e-signature, payments) | 9,600 EUR | 4,800 EUR | 4,800 EUR |
| 4-year total | 63,360 EUR | 85,440 EUR | 83,600 EUR |
| Specific features (mid-term lease, B2B) | Limited | Partial | Complete |
On licence cost alone, custom matches high-end software. The difference lies elsewhere: a 2-point occupancy gain on 140 units let at 2,300 EUR a month brings in about 77,000 EUR a year. A truly unified calendar, avoiding gaps between assignments and double bookings, delivers that gain.
Budget and timeline by scope
| Scope | Price excl. tax | Timeline | Best for |
|---|---|---|---|
| Core: calendar, leases, collections | 30,000 to 40,000 EUR | 3 months | 50 to 120 units |
| Standard: + corporate space, cleaning, reporting | 45,000 to 55,000 EUR | 4 months | 100 to 250 units |
| Full: + owner mandates, accounting, mobile app | 60,000 to 70,000 EUR | 5 months | Third-party managers |
| Maintenance | 400 to 900 EUR/month | Ongoing | All |
| Annual improvements | 5,000 to 12,000 EUR/year | As needed | All |
Compliance points to build in: in Paris, registration numbers, the 90-night cap on short lets of a main residence, change-of-use rules, rent control applying to furnished units and mandatory mobility lease clauses; in London, the 90-night rule for short lets and deposit protection schemes for assured shorthold tenancies. The app can automatically block non-compliant bookings.
Mini case study
Julien, managing director of a company operating 140 furnished apartments in Paris (the logic is identical for a London operator), lets at an average of 2,300 EUR a month with 86% occupancy. He picks the standard scope at 50,000 EUR excl. tax.
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- Occupancy up from 86% to 88%: 140 × 2,300 × 12 × 2% = 77,280 EUR/year of extra revenue
- Management time saved: 25 hours a week at 35 EUR = 45,500 EUR/year
- Year 1 cost: 50,000 + 7,200 of maintenance = 57,200 EUR
The project pays back in under 6 months, then generates more than 110,000 EUR of extra margin a year.
FAQ
Can we keep our current channel manager?
Yes. The app connects through API to the main channel managers, or replaces iCal sync. Budget 4,000 to 8,000 EUR excl. tax per API connector.
How are deposits handled on mid-term leases?
In France a deposit is forbidden under a mobility lease, so the app handles the Visale guarantee or rent insurance, and keeps deposits for standard furnished leases, capped at 2 months' rent. In England, deposits are capped at 5 weeks' rent and must be protected.
Is an e-signature valid for a lease?
Yes, a simple or advanced electronic signature is valid. Cost per signature is 1 to 3 EUR depending on the provider.
Who owns the code?
The contract assigns the rights to the custom code to you. You can change provider without starting from scratch.
Can we start small?
Yes, the 30,000 EUR core covers the essentials in 3 months, then the corporate space and reporting are added in packages of 8,000 to 15,000 EUR.
Let's scope your project. Describe your portfolio, booking channels and current tools, and we will price an app between 30,000 and 70,000 EUR excl. tax, delivered in 4 months. 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.
