I want to create an "API Only" user but can't find the checkbox to do that. I can see "API Enabled" as one of the checkboxes on the profile and permission set pages but I think that's different. How can I create an API only user ?
This is a permission not a special user. You can create a new API only user by setting permission at profile level:-
- Create a new User.
- Create a new Profile or clone existing one
- In new profile at Administrative section check the checkbox "Api Only User" and Save.
- You have created an API only user
When you check the API User checkbox, it restrict the permission of UI based login, you can't use credentials to actually log into the Salesforce instance. It count against API user license.