Quand développer sur mesure plutôt que d'utiliser du prêt-à-l'emploi

Every growing company eventually faces this question: should we build custom software or use an off-the-shelf SaaS tool? The answer is rarely simple, and getting it wrong is expensive in both directions.

When to buy

Buy when the software isn't your competitive advantage. If hundreds of companies have the same need and a mature product exists, building custom is usually a waste of engineering resources.

• Email marketing (Mailchimp, Resend)
• Project management (Linear, Jira)
• Analytics (Google Analytics, Mixpanel)
• Payment processing (Stripe)
• Customer support (Intercom, Zendesk)

When to build

Build when the software IS your competitive advantage, when no existing tool fits your workflow, or when an off-the-shelf tool would require so many workarounds that you'd spend more maintaining the integration than building from scratch.

• Your core product or platform
• Workflows unique to your business that no SaaS tool addresses
• Systems where you need full control over data, performance, or UX
• Integrations that connect multiple internal systems in complex ways

The hidden costs of buying

SaaS tools look cheap at first. $50/month per seat. But add it up across your team, multiply by the number of tools, and factor in the cost of working around features that don't quite fit your workflow.

The real cost of buying isn't the subscription — it's the organizational overhead of adapting your processes to fit the tool's assumptions. Sometimes that adaptation is fine. Sometimes it fundamentally compromises how your team works.

The hidden costs of building

Custom software requires ongoing maintenance, security patching, feature development, and infrastructure management. A tool that took 3 months to build will need continuous investment for as long as it's in use.

The question isn't just 'can we build this?' — it's 'can we afford to maintain this for the next 5 years?'

The decision framework

Ask three questions: Is this a core differentiator? Does an adequate tool exist? Do we have the team to build and maintain it? If the answers are yes, no, yes — build. In most other combinations, buy first and build later if the off-the-shelf solution proves inadequate.