Developer tools
ISO 8601
Parse and validate ISO 8601 / RFC 3339 timestamps, see each part explained, and convert between offsets and time zones.
How it works
Paste a timestamp to see whether it's valid, what kind of value it is, and what each part means. Time distinguishes:
- Z — UTC (offset +00:00).
- Offsets such as +05:30 or −04:00 — they fix the exact moment, but they aren't time zones (they don't know about DST).
- Zoned timestamps with a bracketed IANA zone — the most complete form (RFC 9557).
- Local date-times without an offset — wall-clock readings, interpreted in a zone you choose.
- Date-only values, week dates (2026-W41-3) and ordinal dates (2026-280).
- Fractional seconds up to nanoseconds.
Not every date-like string is ISO 8601: 07/10/2026 is a regional format and is rejected with an explanation. Space-separated forms (allowed by RFC 3339) are accepted with a note.
Worked example
2026-10-07T10:30:00+05:30 breaks down as date 2026-10-07, time 10:30:00, offset +05:30. It's one exact moment: 2026-10-07T05:00:00Z in UTC.
2026-10-07T10:30:00+05:30[Asia/Kolkata] adds the IANA zone (RFC 9557), which also tells software how to handle future DST changes. 2026-10-07T10:30 has no offset: it's a local reading, not a moment, until you say where.
Edge cases handled
- Positive and negative offsets, and Z.
- Offset/zone mismatches (e.g. +01:00[Asia/Kolkata]) are rejected.
- Impossible dates (2026-02-30, month 13) explain what's wrong.
- Durations (P1D) and intervals are recognised but not parsed in Phase 1.
- Basic (compact) format and comma decimals are accepted with notes.