Yes, plain boba tea (also known as bubble tea, pearl milk tea, or tapioca milk tea) should be gluten free (GF).

Boba is a tea drink originating from Taiwan, it usually consists of tea, milk and tapioca balls. The balls or “bubbles” contain tapioca starch and sugar. Tapioca is a starch that is naturally GF and is derived from the roots of the cassava plant. The balls are usually black in color from brown sugar.

Boba tea also sometimes contains sago, which is a starch derived from palm stems. This is also naturally GF. The most common flavors of boba are black or green tea. However, there are other flavors and toppings that can be added. It is important to always check the ingredients of all the components. When checking labels, first look to see if it is labeled GF. If the product is not labeled GF, then watch out for wheat, rye, barley, malt, brewer’s yeast and oat ingredients. If unsure, always contact the manufacturer directly.

Check out this post for how to do product research and how to contact the manufacturer.

Related post: Is Tea Gluten Free?

Reference:

https://en.wikipedia.org/wiki/Bubble_tea