Santekno/tools

Timezone Converter

Convert a datetime across multiple IANA timezones at once. Handles DST, ISO 8601, and naive timestamps.

Processed in your browserUpdated · Jan 2026
Input
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Output
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How to use Timezone Converter

Paste your input on the left, choose the options you want, and the output appears instantly on the right. Everything runs in your browser — none of your data is sent to a server.

  • Paste or type your input in the INPUT panel
  • The output regenerates automatically as you type
  • Use Copy to put the result in your clipboard
  • Click Sample to load a working example

What is Timezone Converter?

Timezone Converter takes a single moment in time and shows it in many IANA zones at once — perfect for cross-team scheduling, meeting planning, log forensics, and verifying server-vs-client timestamp drift. Accepts ISO 8601 with offset (`2026-06-15T12:00:00Z`), naive datetimes interpreted in the source zone (`2026-06-15 09:00` in Asia/Jakarta), or blank for "now". DST transitions are handled automatically via the browser's `Intl.DateTimeFormat`. Default targets: UTC, Asia/Jakarta, America/New_York, Europe/London — override with any subset of the 400+ IANA zones your browser supports. Three output styles: ISO 8601 with explicit offset, locale-formatted, and an aligned table. This tool is part of santekno's developer toolbox — a curated collection of utilities built for engineers who care about speed, privacy, and simplicity.

Common use cases

  • Debugging API payloads and integration issues
  • Inspecting tokens, hashes, or encoded strings during development
  • Generating fixtures and sample data for tests
  • Sharing readable output with teammates in code reviews

FAQ

It uses `Intl.DateTimeFormat`, which the browser backs with the IANA tzdb (the same database `pytz`, Go's `time/tzdata`, and Linux `/usr/share/zoneinfo` use). DST rules including historical changes are baked in.

A naive datetime (no Z, no ±offset) is interpreted in the SOURCE zone you picked. Default source is UTC. To enter a Jakarta wall-clock time, set From = Asia/Jakarta first.

ISO 8601 with offset (`2026-06-15T12:00:00Z` or `+07:00`), naive `YYYY-MM-DD HH:mm[:ss]` (interpreted in From zone), the literal word "now", or empty (also "now").

Abbreviations are ambiguous: "IST" can mean India, Ireland, or Israel; "CST" can mean US Central, China, or Cuba. IANA zones (`Asia/Jakarta`, `America/New_York`) are unambiguous, DST-aware, and the only correct identifiers for software.

No. Conversion runs entirely in your browser using built-in `Intl` APIs. No network call, no logging.