I have seen mixed information about opening times for tourists to visit mosques in Istanbul on Fridays. Some say they are not open until 2:30 pm, others say they are open in the morning, closed for the mid-day prayers and sermon, and then reopen. If you have recently visited mosques in Istanbul on a Friday, please share your experience with opening times. Thanks in advance.
You are right that Friday is a day when access to mosques is more limited because of the importance of Friday services. I suggest you look at any of the Muslim websites that list prayer times specifically for Istanbul, because times change day by day depending on the calendar. Some of the more active mosques are closed for a longer time on Friday before and after prayers. One other consideration, some sites are technically part-mosque, part-museum. Popular tourist sites like Aya Sofya and the mosque-museum formerly known as Chora Church fall into that category and may be more accessible. So ---- it depends.
I will be in Istanbul in November. I googled " prayer times Istanbul November 2025" and all the prayer times as well as sunrise came up.
I would google the specific mosque you are interested in visiting on a Friday and see what times are listed. As noted, it will depend on the prayer times for the specific time of year you are going. Typically a mosque closes to visitors 45 minutes before a prayer time and 15 minutes after, so you have to work around that timing every day. If you can schedule your mosque visits on another day, it would provide more time slots. If you can't, then plan to visit in the afternoon.