Decision guide
What you take on if you build enterprise RAG in-house, what you hand over if you buy a platform, and how to judge both on the same evidence.
Updated 21 Aug 2026
Definition
Build or buy is a decision about which responsibilities you want to own. Neither route is automatically faster or cheaper.
Build when the capability is strategically differentiating, hard requirements cannot be met by available products, and the organisation can own the full lifecycle.
Buy when the implemented product layers meet the workflow and the deployment and support boundary is acceptable. Your teams spend their time on adoption and domain work rather than on the platform itself.
The model and the database are the easy part. Count everything around them, and the cost of changing any of it later.
Weight hard constraints before preferences and demonstrations.
Run the same representative documents, question set, scoring method and reviewer process against the internal prototype and shortlisted platforms.
Pick a real piece of work, agree what a good answer looks like, then go through the results together.