We use following IPs in our cron job executing bots:
188.8.131.52 (IPv6: 2607:5300:60:3d9e::1)
184.108.40.206 (IPv6: 2607:5300:60:6d1::1)
220.127.116.11 (IPv6: 2607:5300:60:205::1)
18.104.22.168 (IPv6: 2607:5300:60:9a3::1)
Please make sure our IPs can reach your cron job scripts/programs.
Our bots will use IPv4 unless the destination server forces us to use IPv6.
A JSON format IP list could be found at https://www.easycron.com/ips.json