All our servers are currently hosted on Amazon AWS eu-west-1 in Ireland. Below is a list of the IPs Hotjar uses to send egress, outgoing, traffic from which you can whitelist if required on your end.
IPs used for outgoing traffic only.
18.104.22.168 22.214.171.124 126.96.36.199 188.8.131.52 184.108.40.206 220.127.116.11 18.104.22.168 22.214.171.124 126.96.36.199 188.8.131.52 184.108.40.206 220.127.116.11 18.104.22.168 22.214.171.124 126.96.36.199 188.8.131.52 184.108.40.206 220.127.116.11 18.104.22.168 22.214.171.124 126.96.36.199 188.8.131.52 184.108.40.206 220.127.116.11 18.104.22.168 22.214.171.124 126.96.36.199 188.8.131.52 184.108.40.206 220.127.116.11 18.104.22.168
The IPs listed above do not cover the actual domain https://insights.hotjar.com. This is due to it being configured on an Amazon ELB, Elastic Load Balancer, which means there are multiple non-static IPs assigned to it. If you need to whitelist this as well, the only option would be to whitelist the domains *.hotjar.com
If you need to, you can see a list of all Amazon IPs in this json file, however it is important to know that these IPs change quite regularly.