XApiKey

XApiKey refers to an API authentication mechanism that uses an HTTP header, commonly named X-Api-Key, to pass a secret key that identifies and authenticates a client to an API service. The key is issued by the service and stored by the client, and the server validates the key against a secure store for each request.

In typical use, a client sends a request with a header such as X-Api-Key: 12345-ABCDE. The server checks the key and, if valid, authorizes access to the requested resources. The header name is case-insensitive according to HTTP semantics, and many services also support alternative methods such as providing the key as a query parameter or within an Authorization header. X-Api-Key is widely used by API gateways, cloud services, and microservices as a simple, stateless form of authentication.

Security considerations are central to its use. Keys should be transmitted only over TLS to prevent interception. Keys should be rotated regularly, scoped to minimal permissions, and associated with individual clients or applications to enable revocation. Do not log API keys, and monitor usage for unusual patterns. While convenient, API keys are generally suited for service-to-service or application-level access rather than user authentication; for user authentication, more robust methods such as OAuth 2.0 or JWT are often preferred, sometimes in combination with API keys for per-application access.

Implementation notes typically involve validating the key against a secure datastore, handling missing or invalid keys with appropriate HTTP responses (such as 401 Unauthorized or 403 Forbidden), and applying rate limiting and IP-based restrictions where appropriate.

See also: API key, Bearer token, OAuth 2.0.