AUTHORIZED API in a Web Application is paid or free for Developers ???

[chegbb23]

Hello everyone.
  I wonder if the integration of the AUTHORIZED API in a Web Application is paying or free for Developers ???

Thank you to answer me please.

[RaynorC1emen7]

The sandbox test account is free https://developer.authorize.net/sandbox/ and the api is free.

The only paid part is for the production account.