How-To: Enable Authorize.Net Sandbox Mode
1) Go to https://developer.authorize.net/hello_world/sandbox/ and sign up for a developer account with Authorize.net
2) Note down your API Login ID, Transaction Key and Secret Question
3) Go into the Funnel Buildr app on your store > Settings > Checkout Settings
4) Enter in your Authorize.net API Login ID from your developer account into the Authorizenet Test Login ID field:
5) Enter in your Authorize.net Transaction Key into the Authorizenet Transaction Key field right below:
6) Click the blue Save button to save the settings.
7) To use the sandbox mode, enable it on the funnel you're wanting to test by changing the Enable Sandbox dropdown to YES:
8) When done testing, change the Enable Sandbox dropdown back to No.
For a list of valid test cards to use for testing, please refer to the Authorize.Net Testing Guide