Build vs Buy an AI Gateway When You Have Residency Requirements

The build case

Building an in-house gateway is a legitimate option, especially for teams with the engineering capacity to maintain it and specific requirements a general-purpose product doesn't meet. A self-built gateway gives full control over exactly how requests are handled, logged, and constrained — nothing about that control is exaggerated.

What residency requirements add to the build cost

A basic routing layer — pick a model, send the request, return the response — is a reasonably scoped project. Adding residency awareness changes the scope: per-request classification logic, a maintained mapping of which providers satisfy which constraints (one that needs updating as regulations and provider offerings change), residency-safe failover, and an audit trail that can answer "where did this specific request go, and why" months later. That's a meaningfully larger and longer-lived engineering commitment than the basic version, and it doesn't stop needing maintenance once it ships.

The buy case

A managed gateway trades some of that control for not owning the ongoing maintenance — someone else keeps pace with new provider APIs, new models, and evolving regulatory context, and residency-aware routing is a feature you configure rather than a system you build and keep current yourself.

How to actually decide

• Does your team have dedicated capacity to maintain this indefinitely, not just build a first version?
• Do your residency requirements change often enough that a hardcoded internal mapping would need frequent updates?
• Is routing infrastructure a place you want to differentiate, or a place you'd rather it just worked?

There's no universally correct answer — it depends on your team's capacity and how central routing infrastructure is to what makes your product actually differentiated.