DevStudio's Unix Timestamp Converter translates between Unix epoch seconds, milliseconds, ISO 8601 strings, RFC 3339 strings, and human-readable dates across any timezone, all inside your browser. Paste an integer and the tool tells you whether it looks like seconds since 1970 or milliseconds and shows the corresponding UTC time, your local time, and the time in any other timezone you select. The opposite direction is also supported: pick a date and time, choose the source timezone, and copy back a Unix timestamp ready for a database column or an exp claim in a JWT. The converter handles common edge cases such as the year 2038 boundary, leap seconds, and the difference between calendar dates and absolute instants, and it can format the output with or without a trailing Z, with explicit numeric offsets, or in the millisecond-precision form used by JavaScript. Because every conversion runs client-side, no timestamps, dates, or timezone selections are sent to a server. Common use cases include debugging a log line where the field is a raw integer of unclear units, building seed data for a test database that needs deterministic timestamps, calculating how long until a token expires, comparing two events whose timestamps were captured in different zones, and converting an ISO timestamp from an API response into a friendly local time during a support call. The tool also shows the difference between the chosen instant and the current moment in human-readable form, which is useful for sanity-checking exp and iat claims in tokens.
Paste the integer into DevStudio's Unix Timestamp Converter and the tool detects whether it is in seconds or milliseconds, then shows the corresponding UTC date, your local date, and the same instant in any timezone you pick. Conversion is instantaneous and runs entirely in your browser, which makes the tool safe for production timestamps that should not be transmitted to a third-party service.
Unix time started as the number of seconds since January 1, 1970 UTC, which is the format used by most operating systems, databases, and JWT exp claims. JavaScript's Date class stores time as milliseconds since the same epoch, so timestamps from browser code are typically a thousand times larger. The converter detects which unit you supplied based on the magnitude of the integer and shows results for both interpretations when ambiguous.
A Unix timestamp represents an absolute instant in time, but humans read it through a timezone. The same integer is rendered as different wall-clock times in New York, London, and Tokyo even though the underlying instant is identical. DevStudio shows UTC, your local zone, and any zone you select side by side, which makes it easy to confirm whether two systems disagree about the instant or simply about the display zone.
ISO 8601 is an international standard for representing dates and times as strings — for example 2024-01-15T14:30:00Z for the fifteenth of January 2024 at half past two in the afternoon UTC. The format is unambiguous, sortable as plain text, and accepted by almost every database and programming language. RFC 3339 is a slightly stricter profile of ISO 8601 used in many internet protocols and JSON APIs.
Choose the source timezone before entering a date, or attach an explicit numeric offset to your input string. DevStudio uses the browser's Intl API to enumerate the IANA timezone database, including daylight saving rules, so conversions account for transitions automatically. To avoid ambiguity in stored data, prefer to record everything as UTC Unix timestamps and only convert to a local zone at display time.