Switcher⇌Roo is app designed by Tyroo for her furry transformation themed art. It has sliders and options that are used to modify depicted characters body and/or personality aspects. Search up switcher-roo tag on e621 to get the idea.
CONTROL lets you connect to other user and change their app settings (manipulate sliders/checkboxes, create new sliders etc.). All changes will be reflected on their side in real-time!
Make your own character, dress them up in various outfits and adjust their body with sliders! Note: this feature is in beta and species support is a bit limited. Also it is disabled by default so you will need to enable it in options.
Note: Current CharViz is considered a legacy feature and won't be updated anymore. CharViz NextGen might be released sometime in the future. It will support all species and all body types enabling a wide range of transformations.
You want to make a character and have a lack of inspiration? Don't hesistate to hit Randomizer button a few times! Works best with CharViz enabled.