Unix Timestamp Converter

A Unix timestamp is how computers store a point in time: as the number of seconds since 00:00:00 UTC on 1 January 1970. It appears everywhere in software, from database records and log files to API responses and JWT claims, and it is genuinely difficult to read by eye. The timestamp converter turns any of these values into a human-readable date instantly.

The tool accepts three formats. Paste a Unix timestamp in seconds and you get the corresponding date. Paste one in milliseconds and it works too, because the converter detects the format from the magnitude of the number: values above roughly 1e11 are treated as milliseconds and smaller values as seconds. Or paste an ISO 8601 string, which is the format most modern APIs return, and it will be parsed directly.

The output gives you the value in every useful representation at once: the Unix timestamp in seconds, the same value in milliseconds, the ISO 8601 string in UTC, and the date rendered in whichever timezone you select. That last one matters more than it first appears, because a timestamp rendered in UTC and the same timestamp rendered in your local timezone are different dates whenever the time falls near midnight.

If you are working with an API, you will usually want the ISO 8601 output, because that is what you should send in a request body. If you are reading a log file, you want the local-time rendering. If you are comparing two values, you want the raw seconds.

One detail worth knowing: Unix timestamps are defined in UTC and have no timezone of their own, so a bare number always means the same absolute moment regardless of where you view it. The "local time" you see in a log or a database table is a formatting decision made when the value was stored or displayed, and it is one of the more common sources of confusion when comparing data from different systems.

Everything runs locally in your browser. No timestamp is sent anywhere.