Rabbi Naftali Dov Amsterdam was born in 1832 in Salant, Lithuania. From his youth he stood out for his diligence and fear of Heaven, so much so that Rabbi Yisrael Salanter, the founder of the Mussar movement, entrusted him with educating his own son. He studied under him in Vilna and Kovno and became one of his foremost disciples. Rabbi Yisrael described his three great students thus: Rabbi Yitzchak Blazer, the scholar; Rabbi Simcha Zissel Ziv, the sage; and Rabbi Naftali Amsterdam, the pietist.

After his marriage he refused any rabbinic post and opened a bakery to make a living, but his teacher forbade him to work there as a simple labourer. In 1867 he became rabbi of Helsinki, where he stayed eight years, then returned to Kovno, where he lived in poverty. Rabbi Yisrael then sent him to St Petersburg as a moreh tzedek alongside Rabbi Yitzchak Blazer; he later served as rabbi of Jasvoyn and Aleksot, before giving up the rabbinate to devote himself entirely to self-refinement and to spreading Mussar in the yeshivot.

After his wife died in 1906 he moved to Jerusalem. He is known through the many dialogues with his teacher recorded in Mussar literature. He passed away in Jerusalem in 1916 and rests on the Mount of Olives.