Never share your serial number on public forums – it can be used to spoof support requests or register fake devices. Only enter it on (URL starting with https://www.hikvision.com ).
The most common way to check your serial number is to attempt to link it to your account on the Hik-Connect Web Portal . Hikvision Serial Number Check Online
Note: URLs may change. If a link is broken, search "Hikvision Online Warranty Inquiry" via Google to find the current official page. Never share your serial number on public forums