Unix Timestamp Converter

What is a Unix timestamp?

A Unix timestamp, also called epoch time or POSIX time, counts seconds since 00:00:00 UTC on 1 January 1970. It is the standard way servers store instants: one integer, no timezone name, and the same value in every language. Human-readable dates are derived from that integer when you need to display them.

JavaScript, Java, and many JSON APIs use milliseconds instead, which adds three digits. 1760000000 and 1760000000000 are the same moment.

How to convert epoch time to a date

1. 1. Paste the timestamp. Use the number from the API, the log, or the token. ISO dates such as 2026-10-02T12:00:00Z work too.
2. 2. Choose the unit. Auto-detect treats 13-digit values as milliseconds and shorter values as seconds. Switch the unit if you already know which one the API uses.
3. 3. Read the result. Copy Unix seconds, milliseconds, ISO 8601, UTC, or your local time.

Seconds, milliseconds, and ISO 8601

REST APIs often mix formats in one payload: a created time in Unix seconds, a client timestamp in milliseconds, and an ISO string in a webhook body. Comparing them by eye is unreliable because a millisecond value looks like a date centuries in the future if you read it as seconds.

ISO 8601 (2026-10-02T12:00:00.000Z) is the form most JSON APIs use when they want a timezone-explicit string. The trailing Z means UTC.

Timestamps in API testing and JWTs

JWT exp, iat, and nbf claims are Unix seconds. When a request fails with 401, convert exp before assuming the signature is wrong. The same check applies to webhook created fields, cache expiry, and mock responses that include updatedAt.

Pair this page with the JWT decoder when you need the raw claims, then come back here to read the dates. Use MockFlow mock APIs when you want a fixture whose timestamps you control.

Related tools

• Developer tools — the full set of free browser utilities.
• JWT Decoder — inspect exp, iat, and nbf claims, which are Unix timestamps.
• UUID Generator — create v4 and v7 ids for the same mock payloads.
• JSON Formatter — pretty-print the response that contains the timestamp.

Frequently asked questions

What is a Unix timestamp?

A Unix timestamp is the number of seconds since 00:00:00 UTC on 1 January 1970, a moment called the Unix epoch. APIs, databases, logs, and JWT claims such as exp and iat store time this way because it is a single integer that does not depend on a timezone.

What is the difference between Unix seconds and milliseconds?

Unix seconds count whole seconds since the epoch. Unix milliseconds count thousandths of a second, so the number is 1,000 times larger. JavaScript Date.now() returns milliseconds. Many backend APIs and JWT claims use seconds. This converter auto-detects the unit and lets you force either one.

Does this epoch converter run in my browser?

Yes. The Unix timestamp converter runs entirely in your browser. The timestamp or date you enter is never sent to a server.

How do I convert a timestamp to a date?

Paste the number into the timestamp field and click Convert. The tool shows Unix seconds, Unix milliseconds, an ISO 8601 UTC string, a UTC clock time, your local time, and a relative description such as “in 2 hours”.

How do I convert a date to a Unix timestamp?

Use the date field, pick a local date and time, and click Convert date. The tool returns both the Unix seconds and the Unix milliseconds for that moment.

Why do API timestamps look like 1760000000?

That is seconds since the Unix epoch. Ten-digit numbers are almost always seconds. Thirteen-digit numbers are almost always milliseconds. JWT exp and iat claims, webhook created_at fields, and many log lines use the ten-digit form.