What is a Unix Timestamp?
A Unix timestamp is the number of seconds that have passed since January 1, 1970 at 00:00:00 UTC. Developers use timestamps because they are compact, language independent and easy for systems to compare.
Where Timestamps Appear
- API responses
- Application logs
- Database records
- JWT expiration claims
- Scheduled jobs and queues
UTC vs Local Time
Most backend systems store time in UTC and display it in the user timezone later. Timezone bugs often happen when an application treats local time as UTC or converts the same value twice.
How to Debug Date Problems
Convert the timestamp to UTC first, then compare it with the expected local timezone. This makes it easier to identify whether the issue comes from storage, API serialization or frontend display.