Kranzler was born in Germany. His family fled the Nazis to the United States in 1937 when he was a child, and he was raised in New York. He studied for a BA (1953) and an MA (1958) at Brooklyn College, for an M.L.S. degree (1957) at Columbia University, and for his doctorate (1971) at Yeshiva University. After working as a school librarian, he joined the faculty of Queensborough Community College of the City University of New York (CUNY) in 1969, and was a Professor in the Library Department there until his retirement in 1988. Kranzler was one of the founders and the first Director of the Holocaust Resource Center and Archives at Queensborough Community College, which has since been renamed the Kupferberg Holocaust Resource Center and Archives.
He was a leading historian on the subject of aiding the Jews during the Holocaust, a field which his works founded. He was among the first to document the activities of Orthodox Jewish organizations, such as the Vaad Ha-hatzala and Agudath Israel. Historian Alex Grobman referred to Kranzler as "the pioneer of research on Orthodox Jewry during the war." He also researched and created awareness for the mid-1944 Swiss grassroots protests, including the mid-1944 Swiss Press Campaign, triggered by George Mantello publicizing the Bratislava Working Group Vrba-Wetzler report. Kranzler was convinced that these actions led to stopping of the transports from Hungary in mid-1944 and enabled the Raoul Wallenberg mission and other important initiatives in Hungary and elsewhere.
Kranzler was a contributor to the Goldberg Commission Report on the Role of American Jews During the Holocaust, and submitted two chapters, one on the Orthodox, called "Orthodox Ends, UnOrthodox Means" and another on the Jewish Labor Committee. He served as Scholar-in-Residence in numerous congregations, on college campuses, and centers, including the Spanish-Portuguese Synagogue (under Rabbi Marc D. Angel) in Manhattan, and Kodima Synagogue in Springfield, Massachusetts (under Rabbi Alex Weisfogel), and the Ohio State University Holocaust Center (under Professor Saul S. Friedman). Kranzler was a Baron Friedrich Carl von Oppenheim Research Fellow for the Study of Racism, Antisemitism, and the Holocaust at Yad Vashem's International Institute for Holocaust Research during 2002–2003, where he engaged in a research project entitled "A Comparative Study on the Worldwide Rescue Effort by Orthodox Jewry During the Holocaust Within the Context of Rescue in General."
Kranzler researched the rescue and aid of Jews during the Holocaust for about 35 years. He published ten books and many articles on the subject, and lectured on the subject in America, Israel, Europe and the Far East. He interviewed and recorded over a thousand people, including some of the major Jewish rescuers such as Hillel Kook also known as Peter Bergson, George Mantello, Rabbi Solomon Schonfeld and close family and associates of rescuers no longer alive, including Rabbi Michael Ber Weissmandl and Recha Sternbuch. He established one of the largest and unique research document and interview (mostly audio) archives on the subject, which it currently at Yad Vashem.
- The Man Who Stopped the Trains to Auschwitz: George Mantello, El Salvador, and Switzerland's Finest Hour, Foreword by Senator Joseph I. Lieberman, Syracuse University Press (March 2001), ISBN 978-0-8156-2873-6
- Holocaust Hero: The Untold Story of Solomon Schonfeld, an Orthodox British Rabbi, Ktav Publishing House (December 2003), ISBN 978-0-88125-730-4
- Thy Brothers' Blood: The Orthodox Jewish Response During the Holocaust, Artscroll (December 1987), ISBN 978-0-89906-858-9
- Japanese, Nazis & Jews: The Jewish refugee community of Shanghai,
- Heroine of Rescue: The Incredible Story of Recha Sternbuch Who Saved Thousands from the Holocaust
- Gutta, Memories of a Vanished World, ISBN 1-58330-779-6
- To Save a World (2 Volumes), C I S Communications, Incorporated (August 1991), ISBN 978-1-56062-089-1
NOTES: Some of the above are co-authored. Additional books not on the subject of are not shown.
- Goldberg Commission Report on American Jewry During the Holocaust
- Encyclopedia of the Holocaust
- The World Reaction to the Holocaust
- Yale Encyclopedia of the Holocaust
- New Dictionary of National Biography[clarification needed]
- "David Kranzler." Contemporary Authors Online. Detroit: Gale, 2001. Literature Resources from Gale. 30 Aug. 2010.
- "Research Fellow Remembered." Institute News - The International Institute for Holocaust Research, no. 11 (Dec. 2007): 42. Accessed 9 July 2015.
- Alex Grobman, Battling for Souls: The Vaad Hatzala Rescue Committee in Post-Holocaust Europe (KTAV, 2003), p. iii
- David Kranzler (2000). The Man Who Stopped the Trains to Auschwitz: George Mantello, El Salvador, and Switzerland's Finest Hour. Syracuse University Press. p. 87. ISBN 978-0-8156-2873-6.
- Dr. David Kranzler, Holocaust Teacher Resource Center, http://holocaust-trc.org/kranzler.htm
- "An Interview with David Kranzler," Sugihara: Conspiracy of Kindness, https://www.pbs.org/wgbh/sugihara/readings/kranzler.html
- Righteous Among the Nations
- Mark Klempner, author of The Heart Has Reasons: Holocaust Rescuers and Their Stories of Courage
- Zegota Council to Aid the Jews in occupied Poland
- List of people who helped Jews during the Holocaust