Go to SETTINGS -> ACCOUNT -> ACCOUNT ACCESS and allow API access. The API is available at https://api.beds24.com.
*The XML functions can be accessed with your Beds24 username and password.
*The JSON functions can be created with a API and prop key which you set yourself in the Beds24 control panel {{#fas:cog}} (SETTINGS)ACCOUNT and {{#fas:cog}} (SETTINGS) PROPERTIES > ACCESS
The default limit is 60 API calls per 5 minutes for an account.