Yes, you can use salted butter for brownies. Salted butter contains added salt, which can add a subtle savory element to your brownies and enhance the overall flavor profile. However, it's important to note that the amount of salt in salted butter can vary depending on the brand, so the saltiness of your brownies may be slightly different each time you use different brands of salted butter.
If you decide to use salted butter in your brownie recipe, you may want to adjust the amount of additional salt called for in the recipe. Reduce or omit the salt if you prefer a less salty taste, or keep it as is if you enjoy the balance of flavors.
If you don't have salted butter on hand or prefer to control the amount of salt in your brownies, you can always use unsalted butter and add salt separately according to your taste preferences.