Timestamp Converter (Unix ↔ ISO)

Timestamps are easy to store but easy to misread. A common source of bugs is mixing Unix seconds with Unix milliseconds, which shifts dates by a factor of 1000. Another common issue is timezone confusion: APIs often return UTC, while dashboards and local machines show local time with offsets and daylight saving rules.

This converter helps you move between Unix time and ISO 8601 quickly. Paste a timestamp, choose the unit (seconds or milliseconds), and get an exact UTC ISO string plus a local-time view. Or paste a date/time string and convert it back to Unix values in both units. When you’re debugging distributed systems, seeing both representations side-by-side saves a lot of guesswork.

ISO 8601 is the safest format to share: it’s unambiguous when you include a timezone (Z for UTC, or an explicit offset). If you paste a date without a timezone, JavaScript interprets it as local time in most cases. That’s why production APIs typically include Z or offsets. When two systems disagree, compare the exact input string and confirm the unit and timezone assumptions.

For everyday developer workflows, you’ll use this tool when inspecting logs, verifying token claims, checking cache expiry, or building test fixtures. It’s designed to be fast and private: you can convert values without installing anything, and you can copy outputs directly into code, SQL, or incident notes.