I was curious now and found
https://www.maximumyield.com/rooting-hormones-organic-stimulants/2/1480"Auxins are one of the main plant hormones that aid in the creation of initial root growth. More specifically, indole acetic acid (IAA) is the natural auxin found in plants that is responsible for natural root stimulation.
IAA is involved in just about every aspect of plant growth and development, including the formation of embryo development, induction of cell division, stem elongation, vascular tissue differentiation, fruit/flower development, tropic behaviors (leaves and stems moving toward the light source) and the induction of rooting.
Most rooting products do not contain IAA but rather a synthetic form of indolebutyric acid (IBA) and/or napthaleneacetic acid (NAA). These rooting hormone products come in different forms, each with their own advantages and disadvantages."
Seems like most rooting products are synthetic Indole-3-butyric acid
https://en.wikipedia.org/wiki/Indole-3-butyric_acid