Two forms to choose from, choose only one

I've got one screen with two API options available (web tool). Both forms include a title and two input fields. The user can only choose one API at the time.

Now, I've tried checkboxes, a dropdown menu to show only one, a tab nav (and that's odd). I've tried to disable the other option's input fields when editing the other... etc. None of them are solutions.

I am drawing blanks. How would you guys solve this?