Is Notre-Dame free to enter?
Yes. Cathedral entry is free, and official reservations are free and subject to availability.

Notre-Dame Companion is an independent reservation-assistance and digital companion service operated by FON Group, Inc. We are not affiliated with, endorsed by, or authorized by Notre-Dame de Paris, the Diocese of Paris, or the official reservation portal. Cathedral entry is free, and official reservations are free and subject to availability. Your payment covers our assistance service and digital companion content, not cathedral entry.
Notre-Dame de Paris is a working cathedral. Entry itself is free. At busy times, a free official reservation may be useful or required, and official availability can change quickly.
Notre-Dame Companion is for travelers who want help with the reservation process plus a clear digital guide for the visit itself.
If you prefer, you can seek the free official reservation yourself. If you want assistance, practical guidance, audio/history content, and support in one place, that is what our paid service provides.