The verdict in three sentences
A custom project management web app for firms (lawyers, accountants, consultants, architects) costs 18,000 to 50,000 EUR for 8 to 16 weeks, whereas a generic Trello or Asana never truly fits the practice. It raises the time-billing rate by 10 to 20 % by recovering hours entered too late or forgotten, and gives margin visibility matter by matter, impossible with a spreadsheet. For a 15-person firm, those recovered hours often represent 40,000 to 90,000 EUR of revenue per year.
Generic tool vs practice app: the math
A generic tool costs little but lets value leak: poorly logged time, fuzzy re-billing, no margin view. A practice app captures what the generic one ignores.
| Criterion | Generic tool (Trello/Asana) | Custom practice app |
|---|---|---|
| Cost | 10-25 EUR/user/month | 18,000-50,000 EUR |
| Time logging per matter | manual, partial | built-in, guided |
| Billing from logged time | no | yes, in 1 click |
| Margin per matter | invisible | real time |
| Observed billing rate | 65-75 % | 80-90 % |
| Fit to practice workflow | weak | full |
The billing-rate difference, even 10 points, quickly amounts to tens of thousands of euros for a firm whose time is its main asset.
What the budget covers
The core handles matters, tasks, time and billing. Advanced modules (client portal, margin analytics, accounting integration) adjust the price.
| Feature | 2026 budget (EUR) | Duration |
|---|---|---|
| Core matters + tasks + milestones | 9,000-15,000 | 4-5 weeks |
| Time tracking + timesheets | 4,000-8,000 | 2-3 weeks |
| Billing + automatic reminders | 5,000-10,000 | 2-3 weeks |
| Margin-per-matter dashboard | 4,000-8,000 | 2 weeks |
| Client portal (document sharing) | 6,000-12,000 | 3-4 weeks |
| Accounting integration (Sage, Pennylane) | 4,000-9,000 | 2-3 weeks |
A typical firm keeps core + time + billing + margin, around 30,000 EUR for 10 weeks.
Mini case study
Me Diop is a partner in a 12-lawyer firm in Paris. Her time-billing rate is stuck at 68 %: too many hours logged from memory on Friday, so underestimated. She commissions a 31,000 EUR practice app with guided time entry and one-click billing, delivered in 11 weeks. The billing rate climbs to 82 % within six months. On a base of 12,000 billable hours/year at 180 EUR/h, those 14 recovered points represent about 302,000 EUR of additional billing: the app pays for itself in under two months of operation.
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FAQ
Why not just use Asana or Monday?
Those tools manage tasks but not billable time or margin per matter. For a firm, that is exactly where lost profitability hides.
How long to go live?
A usable core arrives in 5 to 6 weeks; a full app with billing, margin and client portal takes 10 to 16 weeks.
Does the app connect to my accounting software?
Yes, connectors to Pennylane, Sage or QuickBooks are built for 4,000 to 9,000 EUR and avoid re-keying invoices.
How do you guarantee staff adoption?
Time entry must be faster than the old method: timers, mobile entry and reminders push adoption beyond 85 % within a quarter.
What ROI should I expect?
A 10-to-20-point gain in billing rate typically pays back the project in 2 to 6 months for a firm billing time at 120 EUR/h or more.
Let's scope your project. Tell us your billable headcount, your average hourly rate and the modules you want, with an indicative budget of 18,000 to 50,000 EUR. 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.
