Api League Authentication
API League authenticates with a single API key and nothing else. There is no OAuth, no OIDC, no scopes, no service accounts and no key rotation surface documented — one key grants the whole 55-operation surface, and the plan attached to that key is what varies. Two interchangeable apiKey schemes are declared in the OpenAPI and applied globally, and the provider documents both: `?api-key=YOUR-API-KEY` in the query string, or the `x-api-key` request header. The query-string form is the one the provider leads with in its own examples, and it is the weaker of the two — a key in a URL lands in proxy logs, browser history, referrer headers and shell history. An agent should use the x-api-key header. The terms of use place the consequences on the consumer: the key must be kept confidential, must be stripped before posting code to a forum or GitHub, and the account holder is responsible for any charges or harm from a compromised key.
API League secures its APIs with apiKey across 2 declared security schemes, as derived from its OpenAPI definitions.
Security Schemes
Source
Authentication Profile
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Every security artifact here is available over the APIs.io API and to AI agents over MCP.