A Unix timestamp (also called Epoch time or POSIX time) is the number of seconds that have elapsed since January 1, 1970 00:00:00 UTC — the Unix epoch. It's a simple, timezone-independent way to represent a point in time, widely used in programming, databases, APIs, and logging systems. Milliseconds timestamps are also common, representing the number of milliseconds since the same epoch.

10 digits (e.g., 1705334400) → seconds timestamp. 13 digits (e.g., 1705334400000) → milliseconds timestamp. This tool automatically detects the format based on digit count. If you see a 10-digit number, it's seconds; 13 digits is milliseconds. Some systems also use 16-digit (microseconds) or 19-digit (nanoseconds) timestamps — simply divide by 1000 to convert to standard seconds.

const date = new Date(timestamp * 1000); (for seconds) or const date = new Date(timestamp); (for milliseconds). Then use date.toISOString(), date.toLocaleString(), or other Date methods. To get current timestamp: Date.now() (ms) or Math.floor(Date.now() / 1000) (seconds).

Use datetime.fromtimestamp(ts) for seconds or datetime.fromtimestamp(ts / 1000) for milliseconds. For UTC: datetime.utcfromtimestamp(ts). Modern Python 3.11+ also offers datetime.fromtimestamp(ts, tz=timezone.utc) for timezone-aware results.

The Year 2038 problem affects 32-bit systems that store Unix timestamps as a signed 32-bit integer. The maximum value is 2147483647, which corresponds to January 19, 2038 03:14:07 UTC. After this point, the integer overflows and wraps to a negative value, potentially causing date-related bugs. Modern 64-bit systems don't have this issue for billions of years.

No. A Unix timestamp is always UTC-based and timezone-independent. The same timestamp represents the exact same moment everywhere on Earth. When you convert a local date/time to a timestamp, the conversion accounts for your local timezone offset. When displaying a timestamp as a human-readable date, you choose which timezone to display it in.

Seconds (10-digit) is the traditional Unix standard — compact, sufficient for most use cases, and compatible with older systems. Milliseconds (13-digit) provides higher precision and is used by JavaScript (Date.now()), Java (System.currentTimeMillis()), and many modern APIs. Always check your API documentation to know which format is expected.