Who declared the Old Testament canonical?

The canon of the Old Testament was largely established by Jewish religious leaders and scholars over several centuries, culminating in the decisions made at various councils, such as the Council of Jamnia around 90 CE. However, it was not a single declaration but rather a gradual recognition of certain texts as sacred and authoritative. Early Christians later integrated these texts into their own canon, which was affirmed through various church councils in the 4th century. The Jewish canon is generally accepted to consist of the three main divisions: the Torah, the Prophets, and the Writings.