Infusionsoft is a popular CRM that can integrate with Cardtapp. To configure the integration, you will need to create an API key within Infusionsoft. Only an administrative user in your Infusionsoft account can do this.
Go to Admin > Settings and click on Application in the settings menu
Scroll down to the API section and enter a passphrase in the text box
The API Passphrase is simply a password, or series of words that will be used to generate your unique API key. Be sure to remember your passphrase if you ever need to generate your API key again.
After you enter a Passphrase, click on the Save button to generate the API key
Your API Key is now available under the textbox where you entered the pass phrase. This identifier is what you will need to provide to Cardtapp so that your integration can be configured.