API Authentication

API authentication is the process of verifying the identity of a client before granting access to an API. Without authentication, any request would be accepted regardless of origin, making usage tracking and access control impossible.

Common methods include API keys (simple, per-request header), OAuth 2.0 (delegated authorization with access tokens), and JWT tokens which encode identity and permissions. Each method has different trade-offs in security and complexity.

On RapidAPI, all authentication uses API keys. When you subscribe to an API, you receive a key that authenticates every request and allows the platform to track usage against your plan quota.