Answer

The Kalpasutra is traditionally attributed to Acharya Bhadrabahu Swami.

Explanation

In Jain tradition, Bhadrabahu Swami is regarded as the author of the Kalpasutra, especially in the Śvetāmbara tradition. This sacred text is highly respected for its descriptions of the lives of the Tirthankars, especially Bhagwan Mahavir.

Spiritual Understanding

The Kalpasutra is important because it preserves devotional and historical teachings that help Jain followers remember the lives, conduct, and ideals of the Tirthankars.

Takeaway

So, the commonly accepted answer is: Acharya Bhadrabahu Swami.