The verdict in three sentences
Legal SaaS stays ideal to start, but a growing firm blocked by frozen workflows and constrained billing benefits from a custom module (35,000-80,000 EUR) connected via API. Break-even against licences arrives between 3 and 4 years, with 15%/yr maintenance. The decisive edge: contract automation (clause generation, e-signature) and total data reversibility.
Vertical SaaS vs custom module: the 2026 comparison
SaaS bills per seat and imposes its processes; a custom module is an owned asset, shaped to the firm's workflows. 2026 orders of magnitude for a 20-seat firm.
| Criterion | Vertical SaaS | Custom module |
|---|---|---|
| Entry cost | 0-3,000 EUR setup | 35,000-80,000 EUR build |
| Annual cost | 40-90 EUR/user/mo = 9,600-21,600 EUR | 15% maint. = 5,250-12,000 EUR |
| New seats | +40-90 EUR/mo each | 0 EUR |
| Document automation | limited | unlimited |
| Client portal + e-signature | vendor-dependent | native custom |
| Data reversibility | constrained export | owned database and code |
Over 5 years the cumulative tips toward custom the faster the firm hires.
| Year | SaaS (20 users, 65 EUR/mo) | Custom (55k build + 15% maint.) |
|---|---|---|
| Year 1 | 15,600 EUR | 63,250 EUR |
| Year 2 (cumulative) | 31,200 EUR | 71,500 EUR |
| Year 3 (cumulative) | 46,800 EUR | 79,750 EUR |
| Year 4 (cumulative) | 62,400 EUR | 88,000 EUR |
| Year 5 (cumulative) | 78,000 EUR | 96,250 EUR |
At stable headcount, the crossover exceeds 5 years; but while growing, each new seat adds 480-1,080 EUR/yr of licence where custom costs nothing extra.
What custom automates in a law firm
The real lever is not case management — SaaS does that — but contract drafting and business connectors.
| Automation | Estimated gain | 2026 connector cost |
|---|---|---|
| Contract + clause generation | 1-2 h/file | 6,000-14,000 EUR |
| Secure client portal | -40% email exchanges | 5,000-12,000 EUR |
| Integrated e-signature | -3 days/signature | 3,000-7,000 EUR |
| Accounting/billing connector | -1 day/month | 4,000-9,000 EUR |
| Automatic mobile timesheet | +1-2 billable h/week | 5,000-10,000 EUR |
Mini case study
Me Ndiaye, partner in a fast-growing 20-lawyer business firm, pays 15,600 EUR/yr in SaaS and plans 8 hires over 3 years. Each seat adds 780 EUR/yr of licence, pushing the bill toward 21,800 EUR/yr. She commissions a custom module at 55,000 EUR + 8,250 EUR maintenance, with contract generation and e-signature connected via API. Contract automation saves 1.5 h/file across 400 files/year, i.e. 108,000 EUR of billable capacity at 180 EUR/h. Break-even at 7 months on that gain alone, then full control of workflows and data.
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FAQ
When to move from SaaS to custom for a law firm?
When frozen workflows or constrained billing cost you hours, and from around fifteen seats up. Below that, SaaS (40-90 EUR/user/month) stays cheaper.
Can we keep the SaaS and add custom?
Yes, an API overlay automates contracting or the portal without replacing everything. It is often the best cost/risk trade-off at 35,000-55,000 EUR.
Is e-signature legally valid?
Yes, provided a scheme compliant with the eIDAS regulation at a suitable signature level. Integration costs 3,000 to 7,000 EUR and saves around 3 days per signature.
Who owns the data and code?
With custom, the firm owns the database and delivered source code. Demand a reversibility clause to avoid lock-in, unlike the constrained exports of SaaS.
What is the real gain from document automation?
1 to 2 h per file on drafting contracts and clauses. Across 400 files/year at 180 EUR/h, that is 72,000 to 144,000 EUR of billable capacity recovered.
Let's scope your project. Describe your workflows, headcount and priority automations (contracts, e-signature, portal): we price a reversible API module. 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.
