After you log in to your 123 Form Builder account, click on My Account. In the subsection API Keys, you’ll find yours listed. If the API Key is not displayed, you’ll need to press the Create now link and your API Key will be automatically generated.
The API key can only be retrieved by the parent account. If you have sub-users, this section will not be available. Sub-users will need to contact the parent account to obtain the API key related to the account.