If :ref:`Access Control <sec-features-access_control>` is enabled OctoPrint's API expects an API key to be supplied with each request. This API key can be either the globally configured one, a user specific one or an app and user specific one as generated by the authorization workflow implemented by the bundled :ref:`Application Keys Plugin <sec-bundledplugins-appkeys>` (since 1.3.10).

Clients are advised to implement the :ref:`Application Keys Plugin workflow <sec-bundledplugins-appkeys-workflow>` first and fallback on directing the user to manually supply the the user specific API key. The global key should rarely be used.

The API key must either be supplied in the custom HTTP header X-Api-Key, e.g.

GET /api/files HTTP/1.1
Host: example.com
X-Api-Key: abcdef...

or as a Bearer token in the Authorization header, e.g.

GET /api/files HTTP/1.1
Host: example.com
Authorization: Bearer abcdef...

For testing purposes it is also possible to supply the API key via a query parameter apikey, e.g.

GET /api/files?apikey=abcdef... HTTP/1.1
Host: example.com

Please be advised that clients should use the header field variant if at all possible.

If the key is missing or invalid, OctoPrint will treat the request as it would any unauthenticated anonymous request to the endpoint. That means that any requests without or with an invalid API key targeting other API endpoints than :ref:`Login <sec-api-general-login>` will be denied with a :http:statuscode:`403`.

The global API key can be found in the "API" settings

The user list in the "Access Control" settings shows the API key for users (if available)

The API key options in the "Change password" dialog. Users can generate and revoke their custom API key here.

If not otherwise stated, OctoPrint's API expects request bodies and issues response bodies as Content-Type: application/json.

OctoPrint uses UTF-8 as charset.

That also includes headers in multipart/form-data requests, in order to allow the full UTF-8 range of characters for uploaded filenames. If a multipart/form-data sub header cannot be decoded as UTF-8, OctoPrint will also attempt to decode it as ISO-8859-1.

Additionally, OctoPrint supports replacing the filename field in the Content-Disposition header of a multipart field with a filename* field following RFC 5987, Section 3.2, which allows defining the charset used for encoding the filename. If both filename and filename* fields are present, following the recommendation of the RFC filename* will be used.

For an example on how to send a request utilizing RFC 5987 for the filename* attribute, see the second example in :ref:`Upload file <sec-api-fileops-uploadfile>`.

To make use of the OctoPrint API from websites other than the OctoPrint web interface, cross-origin resource sharing (CORS) must be enabled. This is the case even when the website in question is served from a different port on the same machine and on localhost.

To enable this feature, set the allowCrossOrigin key of the api section in config.yml to true or check the corresponding checkbox in the API settings dialog.

api:
  enabled: true
  key: ...
  allowCrossOrigin: true

Support for CORS can be enabled in the "API" settings

If CORS is not enabled you will get errors like the following:

XMLHttpRequest cannot load http://localhost:8081/api/files. No 'Access-Control-Allow-Origin'
header is present on the requested resource.

.. versionadded:: 1.8.3

To protect OctoPrint against CSRF attacks against the non CORS affected upload endpoints, in case of browser session based authorization the API is protected using the Double Submit Cookie mitigation strategy. On first page load of the UI, the login page or the recovery page, a csrf_token_P<port> or csrf_token_P<port>_R<root> cookie is set that can be read via client-side JavaScript. All requests towards the API that are not GET, HEAD or OPTIONS and rely on cookie based authorization (so not on an API key but rather an active login session) are required to send both the csrf_token cookie as well as an X-CSRF-Token header containing its value.

.. http:post:: /api/login

   Creates a login session or retrieves information about the currently existing session ("passive login").

   Can be used in one of two ways: to login a user via username and password and create a persistent session (usually
   from a UI in the browser), or to retrieve information about the active user (from an existing session or an API key)
   via the ``passive`` flag.

   Will return a :http:statuscode:`200` with a :ref:`login response <sec-api-general-datamodel-login>` on successful
   login, whether active or passive. The active (username/password) login may also return a :http:statuscode:`403` in
   case of a username/password mismatch, unknown user or a deactivated account.

   .. warning::

      Previous versions of this API endpoint did return a :http:statuscode:`401` in case of a username/password
      mismatch or an unknown user. That was incompatible with basic authentication since it was a wrong use of
      the :http:statuscode:`401` code and got therefore changed as part of a bug fix.

   .. note::

      You cannot use this endpoint to login from a third party page via CORS, see above. You can however use it
      to retrieve user information via passive login with an API key (e.g. if you need the ``session`` to authenticate
      on the web socket.

   :json passive:  If present, performs a passive login only, returning information about the current user that's
                   active either through an existing session or the used API key
   :json user:     (active login only) Username
   :json pass:     (active login only) Password
   :json remember: (active login only) Whether to set a "remember me" cookie on the session
   :status 200:    Successful login
   :status 403:    Username/password mismatch, unknown user or deactivated account

.. http:post:: /api/logout

   Ends the current login session of the current user.

   Only makes sense in the context of browser based workflows.

   Will return a :http:statuscode:`204`.

   :status 204: No error

.. http:get:: /api/currentuser

   Retrieves information about the current user.

   Will return a :http:statuscode:`200` with a :ref:`current user object <sec-api-general-datamodel-currentuser>`
   as body.

   :status 200: No error

The Login response is a :ref:`user record <sec-api-datamodel-access-users>` extended by the following fields: