How to convert many Unix timestamps to ISO at once

1. Paste the timestamps

   Drop one timestamp per line into the "Timestamps (one per line)" field. The tool auto-detects seconds vs milliseconds — values with 13+ digits are treated as ms, shorter values as seconds.

2. Press Run

   Result returns `lines` — an array of `<unix> -> <iso>` strings, in input order. Lines that don't parse as numbers are silently dropped, so check the count if you expect a specific length.

3. Output time zone

   ISO output is always in UTC (suffix `Z`). For local time, post-process with `new Date(iso).toLocaleString(...)` or use a different tool that takes a target zone.

4. Where these come from

   Common sources of batch timestamps: server logs (often seconds), JS `Date.now()` exports (always ms), database CSV dumps (depends on the schema). Mix is fine — the tool decides per line.