How would you design cache keys for a multi-tenant API that returns user-specific data?

Design cache keys with tenant and permission scope

Explains cache-key scope for tenant, user, role, locale, filters, response version, and security-sensitive reads.

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I would include every value that changes the response in the cache key. For multi-tenant data that usually means tenant id, resource id, filters, locale, response version, and sometimes user or role scope. A key like orders:{orderId} is risky if the same order id can exist in different tenants or if different users see different fields.

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Tenant isolation, authorization scope, key composition, response versioning, privacy, and cache poisoning risks.

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Cache keys are part of the security boundary in multi-tenant systems. A tiny missing scope can turn a performance feature into a data leak.
I would include every value that changes the response in the cache key. For multi-tenant data that usually means tenant id, resource id, filters, locale, response version, and sometimes user or role scope. A key like orders:{orderId} is risky if the same order id can exist in different tenants or if different users see different fields.
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I would first decide whether the response is tenant-scoped, user-scoped, role-scoped, or public. Public reference data can use broad keys. Tenant data needs tenant scope. User-specific dashboards, permission-sensitive lists, and admin views usually need user or permission scope, or they may not be worth caching. I would also avoid putting raw secrets or personal data directly in key names because keys appear in logs and diagnostics.

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Using only resource id in a tenant-scoped system.
Caching permission-sensitive data under a shared key.
Putting personal or secret data into key names.
Forgetting response shape/version in long-lived cached values.

How would you design cache keys for a multi-tenant API that returns user-specific data?

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