BOSSA is a flash programming utility for Atmel's SAM family of flash-based ARM microcontrollers. The motivation behind BOSSA is to create a simple, easy-to-use, open source utility to replace Atmel's SAM-BA software. BOSSA is an acronym for Basic Open Source SAM-BA Application to reflect that goal.
I have just tested it with ATSAMD21E18A and it seems to work just fine but i'm wondering if ATSAMD21E17D and ATSAMD21E15B are also supported?