There are a multitude of synonyms for the phrase "just like that." Some alternatives include "in a snap," "in a jiffy," "in a trice," and "in a wink." Other possible phrases include "with ease," "effortlessly," and "smoothly." Additionally, "instantly," "immediately," and "right away" can be used to convey a sense of quickness or suddenness. A more casual phrasing might be "no big deal," "no sweat," or "no problem." Overall, the context in which "just like that" is used will determine which synonym works best, but there is an abundance of options available for expressing a similar sentiment.