Principle of Least Privilege

The principle of least privilege (PoLP) says every user, service, and API key should hold the minimum permissions needed to do its job — and nothing more. It limits blast radius: if an account is phished or a key leaks, an attacker inherits only that narrow slice of access instead of the keys to the kingdom. In practice least privilege is less a feature than a discipline — it fights the natural drift toward over-granting because broad access is convenient and revoking it later feels risky. For SaaS builders it applies at every layer: scoped API tokens, per-service database roles, tightly bounded cloud IAM policies, and RBAC roles that match real job functions. Practical note: default new roles to deny and add permissions deliberately, prefer short-lived scoped tokens over long-lived master keys, review and prune access on a schedule (especially after people change teams or leave), and pair least privilege with an audit log so over-broad grants stay visible.