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API Key

PropertyValue
descriptionSecret value used by software to identify or authenticate requests to an API.
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An API key is a secret value used by software to identify or authenticate requests to an API.

It is commonly passed in a request header, query parameter, or other configuration field so the receiving service can recognize the caller, apply quotas, or enforce access rules.

What it does​

An API key gives software a way to present a credential when calling an API.

It is commonly used to:

  • Identify the calling application or project
  • Authenticate API requests
  • Enforce quotas, billing, or rate limits
  • Restrict access to specific services or endpoints
  • Separate production, staging, and development credentials

Core concepts​

Credential, not the API itself​

An API key is one kind of credential used with an API.

It is not the API and it is not the same thing as the application using it.

Secret handling​

API keys should be treated as secret values.

They should not be committed to source control or exposed in public client-side code unless the provider explicitly supports that pattern with strict restrictions.

API key vs token​

An API key and a token are not always the same thing.

Some systems use long-lived API keys, while others use short-lived bearer tokens or more advanced authentication flows.

Common use cases​

  • Server-to-server API calls
  • SaaS integrations and automation scripts
  • Build and deployment tooling
  • Mobile or desktop apps calling approved service endpoints
  • Project-based access to cloud APIs

Practical notes​

  • API keys are often unrestricted by default unless you add explicit usage restrictions.
  • Good practice includes storing keys outside code, loading them from environment variables or secret managers, and rotating them when needed.
  • If a provider supports more secure alternatives for production workloads, use those instead of broad unrestricted keys.
  • Exposure risk is highest when keys are embedded in public repos, browser code, screenshots, logs, or shared config files.

Sources Used​

Frequently Asked Questions​

Is an API key a password?​

Not exactly. Both are credentials, but an API key is typically issued for software-to-software access rather than direct human sign-in.

Is an API key the same as a token?​

No. Some systems use API keys, some use token-based authentication, and some support both.

Should API keys be stored in frontend code?​

Usually no. Unless a provider explicitly documents a safe restricted client-side pattern, API keys should stay on the backend or in secure infrastructure.