How does it tell epoch seconds from milliseconds?

In Auto-detect mode it looks at the magnitude of each number. A value of about a trillion (10^12) or more is treated as milliseconds, because that many seconds would be a date tens of thousands of years in the future. Smaller integers are treated as seconds. If your data is unusual you can override this with the Seconds or Milliseconds setting, which is applied to every numeric line.

Can I mix timestamps and human dates in the same list?

Yes. Each line is parsed independently. Plain integers are read as epoch values, decimals like 1700000000.5 are read as fractional seconds, and anything else is handed to the browser date parser, so ISO 8601 strings, "2026-12-25 18:30:00" and "Jan 1 2030" all work side by side.

Is the conversion timezone-aware and does it handle daylight saving?

It is. The output column is rendered through the Intl time-zone database built into your browser, so each row uses the correct UTC offset for its own instant — a July timestamp and a January timestamp in the same zone will show different offsets if that zone observes daylight saving.

What does the relative column mean?

It shows how far each instant is from the current time, such as "3 hours ago" or "in 2 days". The clock updates every second, so a row that says "in 1 minute" will roll over to "1 minute ago" as real time passes.

What formats can I export?

You can copy or download a CSV with columns for the original input, epoch seconds, epoch milliseconds, ISO 8601 UTC, UTC wall-clock, your chosen zone, the offset and the relative label. The same data is available as a JSON array of objects for piping into scripts.

Is my data sent anywhere?

No. All parsing, time-zone math and exporting happen locally in your browser using standard web APIs. Your list is auto-saved in this browser so it survives a refresh, but it never leaves your device.

Batch Timestamp Converter

A batch timestamp converter for developers who have more than one value to decode. Instead of pasting timestamps one at a time, drop an entire column of Unix epoch values or dates into the box and get every one converted in a single pass — with epoch seconds, epoch milliseconds, ISO 8601, a UTC wall-clock, your chosen time zone, the live UTC offset and a human relative label, all lined up in a table you can copy or export.

It is built for the everyday data-wrangling that single-value converters make tedious: log lines with created_at epoch columns, a CSV export full of millisecond timestamps, a list of event times pulled from an API, or a spread of dates you need to normalise to one zone before a meeting. The tool auto-detects whether each number is in seconds or milliseconds, accepts free-form dates alongside raw integers, and never makes you guess which row failed — anything it cannot parse is listed separately with the reason.

How it works

Each line of your input is parsed on its own. A bare integer is treated as an epoch value; in Auto-detect mode the tool decides seconds-versus-milliseconds by magnitude (roughly, 13-digit and larger numbers are milliseconds), and you can override that with the Seconds or Milliseconds setting when your data is mixed. Decimal values such as 1700000000.5 are read as fractional seconds. Anything that is not numeric — ISO 8601 strings like 2026-05-30T09:15:00Z, 2026-12-25 18:30:00, or Jan 1 2030 — is handed to the browser’s own date parser.

Every resolved instant is then formatted through the Intl time-zone database that ships with your browser, so the output column reflects the correct daylight-saving offset for that specific moment. A live banner at the top shows the current Unix time, ticking every second, with one-click copy in seconds or milliseconds and an Add now button that appends the current timestamp to your list. Click any value cell to copy just that figure, or use the export buttons to take the whole converted set as CSV or JSON.

Example

Paste a mixed batch:

1700000000
1700000000000
2026-05-30T09:15:00Z
Jan 1 2030

With the output zone set to Asia/Tokyo, the converter resolves the first two lines to the same instant (one is seconds, one is milliseconds), renders all four in Tokyo local time with a +09:00 offset, and adds a relative label for each. Switch the zone to America/New_York and every row instantly re-renders with the matching eastern offset — -05:00 in winter, -04:00 in summer — without you touching the input. Hit Download CSV and the table lands in your spreadsheet ready for analysis.

Everything is computed in your browser. Your list is auto-saved locally so it survives a refresh, and no data is ever uploaded.