How would you implement EU data residency for a SaaS platform?
Reported in King European engineering loops. Often appears in enterprise and platform interviews at EU cloud and SaaS companies.
Interview scenario
Context for King candidates:
Enterprise customers request that all personal data remains in the EU. Explain architecture and rollout strategy.
Model answer
Try answering aloud first
Cover trade-offs, structure, and a concrete example before revealing the baseline response.
How to frame this at King: Connect your answer to measurable impact, clarity of thought, and trade-offs the team cares about. Below is a strong baseline response you can adapt with your own project examples.
Start with region-scoped tenancy: assign tenants to EU partitions and enforce routing at API, queue, and storage layers. Prevent accidental cross-region replication with policy guards and CI checks.
Classify data by sensitivity and define allowed processing zones. For global control planes, store only minimal metadata outside region and encrypt with region-bound key management.
Provide customer-facing guarantees: residency controls, audit exports, and incident response commitments. Roll out with migration tooling, phased cutovers, and rollback playbooks to reduce risk.
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