Build vs Buy AI: How to Make the Right Decision

The False Dichotomy

Build vs buy isn't binary. There's a spectrum:

• Off-the-shelf SaaS: Buy a complete product (Jasper, Copy.ai, Notion AI)
• API + configuration: Use OpenAI/Anthropic API, configure with prompts (medium build)
• Open-source + customisation: Self-host Llama, fine-tune for your use case
• Train from scratch: Only justified for frontier research teams

Most businesses should be at level 2 or 3, not level 1 or 4.

When to Buy

• The use case is generic (content writing, meeting summaries, basic support)
• Speed to value is critical (need results in days, not months)
• Your team has no AI engineering capacity
• The task is not a competitive differentiator
• Compliance requirements are manageable with vendor's data processing agreements

When to Build (or Customise)

• The use case involves proprietary data that can't leave your systems
• The workflow is deeply specific to your business (no SaaS covers it)
• You need deep integration with internal systems (ERP, custom CRM)
• This is a core competitive advantage you want to own
• At scale, build is significantly cheaper than SaaS licensing

The 5-Factor Decision Matrix

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