Konwerter znaczników Unix

What a Unix timestamp is and when you need this

A Unix timestamp is simply a count of seconds since a fixed moment called the epoch: midnight UTC on 1 January 1970. Because it is just one integer with no timezone attached, it is the format machines love and humans cannot read at a glance, which is exactly why you need a converter. You reach for this tool when a log line, a database column, an API response, or a token shows a raw number like 1753660800 and you need to know what date and time it actually represents — or the reverse, when you have a date and need the integer a system expects. It converts a timestamp into a readable local and UTC date, and turns any date and time you pick back into a timestamp.

Seconds or milliseconds, detected for you

The single most common source of confusion with epoch time is the unit. Classic Unix time and most back-end APIs measure in seconds, but JavaScript’s Date.now() and many front-end systems measure in milliseconds — a thousand times larger — and mixing the two throws dates off to the wrong year entirely. This tool detects which you pasted: if the number is large enough to only make sense as milliseconds (roughly a trillion or more) it treats it as milliseconds, otherwise it treats it as seconds. It then shows you several views at once so there is no ambiguity: the time in your own local timezone, the same instant in UTC, the ISO 8601 form (2025-07-28T00:00:00.000Z), and both the seconds and milliseconds values so you can copy whichever your target system wants.

Both directions, including the past

Going the other way, you pick a date and time in your local timezone and the tool returns the corresponding seconds and milliseconds counts along with the UTC and ISO forms. There is a “Now” button for grabbing the current instant, which is handy when you are testing or need a fresh value on the spot.

• Reading a JWT’s exp, iat or nbf claim to see when a token was issued or expires — these are Unix seconds.
• Making sense of a created_at or updated_at integer from an API or database.
• Checking a cron run, a rate-limit reset header, or a cache expiry.
• Timestamps before 1970 are simply negative numbers, and the tool converts those too.

If you are building against timestamped fields in your own integration, our developer documentation notes which fields are epoch seconds versus ISO strings, so you can match formats without guessing.

Timezones, and the year-2038 caveat

Remember that the timestamp itself carries no timezone — it is an absolute instant. The “Local” line depends on your browser’s current timezone setting, while the UTC and ISO lines are the same for everyone on Earth, so quote the UTC value when you are comparing notes with someone in another region. Two historical quirks are worth knowing: leap seconds are not represented in Unix time, and systems that still store the timestamp in a signed 32-bit integer will overflow on 19 January 2038 (the value 2147483647), which is why modern software has moved to 64-bit timestamps.

Computed locally, never uploaded

All of this runs in your browser using its built-in date handling. The timestamps and dates you enter — which might come from private logs, an internal system, or a token you are debugging — are converted on your own device and are never sent to a server, stored, or logged. Nothing about the values you check leaves your machine, so you can safely paste sensitive log lines. There is no history and no upload; refresh the page and it starts clean.