Originally published at vatnode.dev. The version on vatnode.dev is the canonical source — refer to it for the latest content.
Build vs Buy: Should You Call VIES Yourself or Use an API?
VIES is free and public, so the first instinct is almost always the same: we'll just call it ourselves. That instinct is not wrong. For some teams it is exactly the right call. But "free" describes the endpoint, not the integration, and the gap between the two is where the real decision lives.
This is a build-vs-buy framework, not a pitch. The scope is the EU-27 plus XI (Northern Ireland), which is what VIES covers. The goal here is to enumerate the actual work honestly — what you own when you build, what you offload when you buy — so you can decide which side of the line your case falls on. For most low-stakes, low-volume cases, building is fine. The point is to know that before you commit, not after.
The "we'll just call VIES" assumption
