What Is API Key?
An API key is a unique string of characters used to identify and authenticate an application, service, or user when making requests to an application programming interface (API). Rather than a username and password, the calling system includes the API key in each request, allowing the API provider to verify the caller's identity, enforce rate limits, and control which data or functions it can access. API keys are widely used to connect software components — for example, letting a web application call a payment processor, a mapping service, or an internal microservice. They are typically simpler to implement than more advanced authentication methods like OAuth, but they generally do not expire automatically, do not identify an individual user, and often grant broad access once issued, which is why they are treated as a distinct category of non-human identity requiring careful handling.
Why It Matters
API keys are one of the most commonly leaked types of credential, precisely because of their simplicity: they are plain strings that can be accidentally committed to public code repositories, hardcoded into mobile apps, logged in error messages, or shared in chat tools without anyone noticing. Unlike passwords, they rarely have built-in expiration or MFA, so a leaked key can remain valid and exploitable indefinitely unless someone actively revokes it. Because API keys frequently grant broad, sometimes admin-level access to an entire service, a single exposed key can let an attacker exfiltrate data, rack up cloud costs, or pivot into connected systems. This pattern is a major contributor to the finding that 80% of identity breaches involve a non-human identity (OWASP NHI Top 10, 2025) — API keys sit squarely at the center of that statistic, alongside tokens and service account credentials.
How Cydenti Helps
Cydenti continuously discovers API keys across your codebases, cloud configurations, and SaaS integrations, tracking which application owns each key, what scope it holds, and whether it shows signs of exposure such as appearing in a public repository. This gives security teams a clear, prioritized view of which keys need rotation, tighter scoping, or immediate revocation, rather than discovering a leak only after it has been exploited. The result is faster detection of exposed keys and fewer standing, over-permissioned credentials in your environment.
Explore →Frequently Asked Questions
What is the difference between an API key and an OAuth token?
An API key is typically a static, long-lived string that identifies an application to an API, with no built-in expiration or user context. An OAuth token is usually short-lived, tied to a specific user or scope of consent, and can be refreshed or revoked as part of a defined authorization flow, making it generally more secure for user-facing access.
What should you do if an API key is leaked?
Revoke the exposed key immediately and issue a new one, then update every system that depends on it. Investigate logs for unauthorized use during the exposure window, remove the key from any code repository history where it appeared, and review whether the key's scope was broader than necessary before reissuing it.
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