API keys are one of the primary components of API authentication and security; they are the API equivalent of your Kraken account's username and password.
API keys are required to call any of the account specific (private) API endpoints, such as the account data, trading, and funding, and earn endpoints. API keys are not required to call the market data (public) API endpoints, as the market data endpoints are not associated with any specific Kraken account.
API keys can be used by any software that interacts with our markets and accounts, such as our REST API command line clients, third party mobile apps and trading platforms, third party trading bots, and various other products/services.