The Biblioteca delle Oblate is a public library located in the heart of Florence, just a few steps away from Piazza Duomo. It's located inside a former 14th-century convent, and it offers a cultural space for reading, studying, and engaging in various activities. It has plenty of study seats, free Wi-Fi, and a conference room.
They also have a café on the upper floor, which has one of the most incredible views of the Brunelleschi's Dome.
Plus, they also have free toilets in case you need them :)