Moster grew up in Borough Park, Brooklyn, one of 17 children in a Yiddish-speaking Hasidic family. He attended a Belzyeshiva where secular studies were limited. After his yeshiva studies, Moster attended Touro College, and then CUNY's College of Staten Island. He earned a Master of Social Work degree at the Silberman School of Social Work at Hunter College in 2015. His education in his yeshiva focused mostly on religious studies, causing him several challenges applying for and studying at college. While studying for his degree in social work, Moster founded YAFFED. He served as President of the organization from 2012-2016, and is currently Executive Director. Concerned that many other students in the ultra-Orthodox community might struggle, as he did, in trying to apply to college and learn skills that would enable them to make a living, Moster founded the non-profit organization, with the aim of ensuring that ultra-Orthodox students in private schools receive the secular education mandated by the State of New York. Public education organizations and staff are often unaware of their responsibilities to students at private and religious schools. Moster discussed the problem of secular education with New York superintendents who have large Hasidic communities in their district. Through YAFFED, Moster is also hoping to raise the awareness of ultra-Orthodox educational needs in the Jewish community. The mission is to ensure that all students acquire the knowledge and skills necessary to earn a livelihood and to allow personal growth. In an interview with The Jewish Daily Forward, Moster noted that his approach to community organizing is not the traditional one. His style is "to get to those people who do believe in education, and enable them to speak up and ask their leaders to make some changes so their children can have a better future". When publications in the insular community refused to publish information, Moster is willing to take a more direct approach, pursuing letter writing campaigns and direct billboards. Moster is also engaged as a public speaker, on radio and at public events such as Limmud.
Family
Moster married Miriam Lipsius on August 1, 2013. She is a writer who received her MFA from Hunter College, where she has taught creative writing.
