In order to use the Betting API, you need to have an Application Key. The Application Key identifies your API client. Two App Keys are assigned to a single Betfair account, one live App Key and one delayed App Key.
You must pass the Application Key with every HTTP request. You do this by setting the HTTP header with the value of the key assigned by Betfair.
X-Application: APP_KEY_ASSIGNED
You can create an Application Key for your Betfair account using the createDeveloperAppKeys operation or by using the Accounts API Visualiser. Please see the API Reference Guide for details of this operation.
Please note: the X-Application header is not required when using the createDeveloperAppKeys or the getDeveloperAppKeys service.