Zoroastrianism, in spite of its small current number of adherents, has played a huge role in the study of comparative religion. Not only was it a cohort of the ancient Vedic Hinduism, but also had a huge influence on the development of Judaism and Christianity.
This part of the site has complete online editions of the Sacred Books of the East’s Zoroastrian texts: the three volume Avesta series, as well as the five volume Pahlavi series.
The scared texts are HERE. Enjoy!