APIs
api
security
authentication
What is API Key?
Definition
An API key is a unique string identifier used to authenticate requests to an API. It is typically passed as a header (X-API-Key) or query parameter. API keys identify the caller but do not authenticate users — they authenticate applications.
Why It Matters
API keys are the simplest form of API authentication. They control access, enable rate limiting, and track usage per client. However, they are less secure than OAuth tokens because they do not expire and cannot be scoped to specific user permissions.