2026-06-10
What is a Unix timestamp?
A practical explanation of Unix timestamps, the Unix epoch, and how developers use epoch time in APIs and logs.
A Unix timestamp is a number that represents time as an offset from the Unix epoch: 1970-01-01T00:00:00Z. In most backend APIs, the number is counted in seconds. In many JavaScript contexts, the number is counted in milliseconds.
Unix timestamps are compact and timezone-neutral, which makes them useful in databases, queues, logs, and API payloads. The tradeoff is readability: 1735689600 is not obvious until it is converted.
Use the Unix Timestamp Converter to inspect a value, then compare it with the ISO 8601 Converter if you need a human-readable form.
Why developers use it
Epoch time is easy to sort, compare, and store. It avoids ambiguous local timezone strings and is widely supported across languages.
What to check
The most important check is the unit. A seconds timestamp and a milliseconds timestamp can look similar but represent very different dates if parsed incorrectly.