The most important part of API configuration is your “API Key”. This is the secure number that assures that only authorized developers can access your account via API.
Please, do NOT share this key with nobody else, otherwise there’s the risk of unauthorized access to your application that might be very harmful!
To generate API key,
On the Navigation bar, point to Company profile and click Settings.
On the Settings page, click API.
On the API tab, click Edit to switch to editing mode.
Click Generate. Under the API-key label, the sequence of digits and letters appears.
Click Save.
Give this API key for developers of external application that needs to be connected with your account.