Sandbox Mode is a basic test tool normally for developers that completely simulates the process of payment, error responses, and reports. If you wish to know how it feels to make/receive payment, this is a featured tool that you can use.
First, you will need to create a Sandbox account at https://developer.authorize.net/sandbox/. Make sure to know the API login and Transaction Key. And this is also not the same as the Sandbox Mode on your live account.
Once you have created your account at https://developer.authorize.net/sandbox/, you will receive an email from them about the details of your new developer/test account. You will also receive dummy credit card numbers which you can run your simulation.
a. Click on the Authorize.Net payment field.
b. Click on the Authorize.Net wizard icon:
c. Click the Settings icon on the top-right corner of the wizard:
d. Swipe the Sandbox Mode to Yes under the Additional Gateway Settings tab.
e. Scroll down to the bottom and click the Continue button. Close the wizard and save the changes.
Once done, you may run your form with Authorize.Net payment tool to simulate payment transactions after you have completed the wizard. Note: Please take note that your form will consider submissions as an actual payment.
For questions, please post it below!