YES. Classic Dosas are naturally Gluten free. They are made just using Rice and Lentils (and fenugreek seeds), ground into batter and fermented. But make sure to check the type of dosa if you are purchasing/ordering stores or restaurants. Many varieties of Dosas exists like "Maida Dosa", "Wheat Dosa", "Rava Dosa" and possible few others that are NOT GLUTEN FREE. Make sure to check ingredients or ask your waiter (if at restaurants) just to make sure.

Check these naturally Gluten free dosas here:
1. Murungai Keerai Dosai (Drumsticks Leaves Black Gram Dosa)
2. Karuppu Ulundhu Dosai (Whole Black Gram Dosa)
3. Vendakkai Dosa (Okra/Lady’s Finger Crepes)
4. 15 Bean and Brown Rice Adai Dosa
5. Sprouted Mung Beans Dosa
6. Sada Dosa (Plain South Indian Crepe)
7. Sprouted Ragi Dosa
8. Classic Adai

For more recipes check here: Dosas and Idli Recipes