# API Key

[](https://help.qlik.com/talend/en-US/talend-data-catalog/Content/developer-guide/application-programming-interface-rest-api/api-key.htm)

All API methods with a few exceptions take a header parameter

> api-key

to allow user authentication. A valid value of the

> api-key

can be obtained by calling the API method POST

> /auth/loginPlainText

or POST

> /auth/login

. If you call POST

> /auth/loginPlainText

the response string itself can be used as the

> api-key

. If you call POST

> /auth/login

the

> result

property of the response object can be used as the

> api-key

.

If you are making API calls via the MM REST API SDK Documentation (or REST API UI), you only need to login once by providing the username and password and clicking on the Login button in the upper right corner. The MM REST API UI will inject the

> api-key

header in all subsequent calls.

An

> api-key

will become invalid after a

> /auth/logout

call is made, the Login timeout is reached, or the Logout button in the upper right corner of the MM REST API UI is clicked.

Note that we renamed the header parameter from

> api\_key

to

> api-key

in MM 11.1.0.