Natural detergent recomendation?

Hi all! I'm new to cloth diapering and have got a lot of about thirty second hand. Mostly Charlie banana. I have personally always been sensitive to detergents and switched to the castile bar, washing soda, and borax mix for my clothes. However I've read that it isn't suitable for cloth diapers. Since it's a soap and not a detergent it doesn't have a surfactant to lift as well can build up on the fibers which when dealing with waste can turn pretty dangerous. Is there one you guys have used that isn't totally synthetic that has worked well on your diapers and sensitive skin?