What is API Key?
1 min read
Updated 2026-02-05
A unique identifier used to authenticate requests to an API. API keys should be kept secret and never exposed in client-side code or public repositories.
Understanding API Key
API keys act as a simple form of authentication, identifying the calling program to the API. Unlike passwords, API keys are typically used for server-to-server communication. When compromised, attackers can make requests on your behalf, potentially accessing sensitive data or incurring costs.
Examples
- Hardcoded API keys in JavaScript files served to browsers
- API keys committed to public GitHub repositories
- Sharing API keys in environment variables without proper access controls
How to Prevent
- Store API keys in environment variables or secret management systems
- Use different keys for development and production
- Implement key rotation policies
- Set up alerts for unusual API usage patterns
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