Unix Timestamp Converter

The Unix Timestamp Converter works both ways between epoch numbers and human-readable dates in two side-by-side panels that stay in sync. The Timestamp → Date card accepts a value in seconds or milliseconds — values above one trillion are automatically treated as milliseconds — and instantly shows local time, UTC in RFC 7231 format, ISO 8601, and the equivalent seconds and milliseconds. The Date → Timestamp card works the other way: pick a date and time with the datetime-local picker at second precision and the Unix seconds and millisecond values appear immediately. A Now button stamps the current moment into both panels, and Send to date picker / Send to timestamp buttons push a valid conversion across so you can continue editing from either side. Invalid input never fails silently — each card shows guidance until a valid value is entered, and the send buttons disable until there is something real to convert. This is the fastest way to decode an epoch timestamp in a log line, build a timestamp for a cron-based test, or check what date 1700000000 actually corresponds to in your timezone.

1. 1

   Type a Unix timestamp in seconds or milliseconds into the Timestamp → Date card.

2. 2

   Read local time, UTC (RFC 7231), ISO 8601, seconds, and milliseconds instantly.

3. 3

   Use Send to date picker to push a valid timestamp into the datetime field on the right.

4. 4

   Pick a date and time in the Date → Timestamp card to compute Unix seconds and milliseconds.

5. 5

   Press Now at any point to reset both panels to the current moment.

• Decoding epoch values from API responses or log lines into readable dates.
• Converting a scheduled release time into an epoch for a cron or cache TTL.
• Comparing timestamps in seconds versus milliseconds when debugging an integration.
• Getting the ISO 8601 string for an event to embed in JSON or a database record.
• Computing expiry timestamps for JWT or short-lived tokens during testing.
• Synchronizing test fixtures with the current time via the Now button.

• Check whether an API expects seconds or milliseconds before building requests — the tool handles both, but your client must too.
• Remember the heuristic: values above one trillion are treated as milliseconds, which matches most modern APIs.
• Use ISO 8601 UTC (the third field) for logs and storage; it is unambiguous across timezones.
• Be aware the datetime picker interprets input in your local timezone — conversions shown there reflect that.
• Do not rely on the browser local rendering for server-side decisions; server clocks may differ from yours.
• For pre-1970 timestamps, use the timestamp-to-date direction, since the picker may not support early dates.

• Paste large API numbers directly — the millisecond heuristic saves you from dividing by 1000 by hand.
• Use the Now button before any test so both sides start from the current moment.
• Grab the ISO 8601 field for JSON payloads; it is the safest cross-timezone representation.
• Round-trip with the Send buttons: convert a date to epoch, then push it back to confirm it matches.