Baking powder does not contain any ingredients that are derived from animals or the byproducts of animals, therefore it is suitable for vegans.
There does not seem to be any variation of baking powder that is not vegan-friendly, so it shouldn’t matter which brand of baking powder you end up choosing. With that being said, if you’re ever unsure, it’s always worth checking the label for the ingredients list.
Here is a list of brands that we know are definitely suitable for vegans as we checked them ourselves:
Argo (Double-Acting and Kosher)
Bob’s Red Mill (Double-Acting, Non-GMO, and Kosher)
Clabber Girl (Double-Acting and Kosher)
Davis (Double-Acting and Non-GMO)
Rumford (Double-Acting, Non-GMO, and Kosher)