Buy vs build business software: the 2026 decision

The verdict in three sentences

The buy-vs-build decision is not about price alone: it turns on process specificity, competitive edge and 5-year TCO. Buying (SaaS) wins for standard needs, small teams and short horizons; building (custom) wins when the software IS the business, integrations run deep, or user count makes the subscription explode. The scoring grid and break-even curves below turn intuition into a defensible decision.

The decision criteria

Seven criteria drive the call. Each leans toward buy or build:

The break-even curves

Cumulative cost depends directly on user count. Example: SaaS at 60 EUR/user/month vs build at 90,000 EUR + 20 %/year maintenance.

Break-even here lands at 50 users: below it, buy; above it, build, all else equal.

The scoring grid

Score each criterion 0 (clear buy) to 5 (clear build), weight, sum:

Weighted score < 2 -> buy; 2 to 3.5 -> hybrid (SaaS + custom modules); > 3.5 -> build.

Mini case study

David is COO of a logistics-services firm in Marseille, 65 users. The SaaS in scope costs 65 EUR/user/month, or 50,700 EUR/year, and can't run his routing algorithm, his real differentiator. Over 5 years: 253,500 EUR of subscription, without owning the IP. A custom build at 110,000 EUR + 20 %/year maintenance totals 220,000 EUR over 5 years, with the proprietary algorithm and zero dependence. His weighted score reaches 3.8: he builds, saves 33,500 EUR and protects his competitive edge.

FAQ

Is buy-vs-build a binary choice? No, hybrid is often optimal: SaaS for the standard (payroll, accounting) and custom for the differentiating core. That's the answer for most middle scores.

How do I factor in speed? Buying ships in weeks, building in months. If time-to-market is critical, start on SaaS then internalize what becomes strategic.

Is vendor lock-in really a cost? Yes: it's paid in exit cost, imposed price hikes and refused evolutions. Quantify it in the 5-year TCO.

What if no SaaS covers 70 % of the need? That's a strong signal toward build or hybrid: workarounds on an ill-fitting SaaS often cost more than custom.

At what budget does custom make sense? Rarely below 50,000 EUR of build, but the real trigger is the 5-year TCO curve crossing, not an absolute threshold.

Let's scope your project. Give us your user count, differentiating processes and horizon: we'll produce your scoring grid and break-even curves. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.