Navkar Mantra is not written by any single author. In Jain tradition it is considered anadi (beginningless) and eternal, a foundational prayer that venerates the Panch Parameshti (Arihant, Siddha, Acharya, Upadhyaya, and all Sadhus). There is no specific human author attributed to it in authentic Jain sources. It is cited and used across both Digambar and Shwetambar traditions as a timeless mantra. You can read more here