I’m afraid we don’t currently support API Only users. The beauty of OAuth, however, is that your integration (and therefore your developers) don’t need to have a permanent copy of your password. Connecting your integration to your FreeAgent account involves a one time exchange of your FreeAgent credentials, meaning you could create the level 7 user, sit down with your developers and enter the user’s email and password combination yourself, and the integration will be given an access token (and a refresh token, which is used to keep the access token alive). Going forward, these tokens are all that’s needed to maintain the connection between your integration and FreeAgent, meaning you never have to part with your password and your developers won’t be able to directly login to FreeAgent. It’s worth highlighting that, whilst your developers won’t have access to the FreeAgent front-end, they’ll still be able to pull sensitive information through the API. You should consider which information is required for the functionality of your integration and set the minimum permission level to achieve these goals.
I hope this helps!