NTP is the internet standard for keeping track of time. It’s a protocol used to synchronize computer clocks for time reference.
The following is a list of publicly available NTP servers.
- Google Public NTP
- time.google.com
- time1.google.com
- time2.google.com
- time3.google.com
- time4.google.com
- Cloudflare NTP
- time.cloudflare.com
- Facebook NTP
- time.facebook.com
- time1.facebook.com
- time2.facebook.com
- time3.facebook.com
- time4.facebook.com
- time5.facebook.com
- Microsoft NTP
- time.windows.com
- Apple NTP
- time.apple.com
- time1.apple.com
- time2.apple.com
- time3.apple.com
- time4.apple.com
- time5.apple.com
- time6.apple.com
- time7.apple.com
- time.euro.apple.com
- NIST Internet Time Service (ITS)
- time-a-g.nist.gov
- time-b-g.nist.gov
- time-c-g.nist.gov
- time-d-g.nist.gov
- time-a-wwv.nist.gov
- time-b-wwv.nist.gov
- time-c-wwv.nist.gov
- time-d-wwv.nist.gov
- time-a-b.nist.gov
- time-b-b.nist.gov
- time-c-b.nist.gov
- time-d-b.nist.gov
- time.nist.gov
- utcnist.colorado.edu
- utcnist2.colorado.edu
This is by no means a complete list, but should be enough to get started.