Which is the Jain holy book

There isn’t a single “holy book” in Jainism. The sacred writings are organized in two broad traditions:

• Śvetāmbara canon: a collection of Agamas (scriptures) believed to be spoken by the Tirthankaras and preserved by the monks.
• Digambara tradition: traditionally holds that the original Agamas were lost or not fully preserved; they rely more on later canonical summaries and commentaries.

A widely respected Jain text used across traditions is the Tattvartha Sutra by Umāsvāti, which succinctly outlines Jain philosophy and path and is accepted by both Śvetāmbara and Digambara traditions.

If you’d like, I can explain how the two canons differ in content and emphasis, or point you to specific Jain texts that cover Jain philosophy, ethics, and practice.