How accurate are the displayed times?

They're computed from your device's clock plus each zone's IANA offset rules. Accuracy is bounded by your system clock; sync via NTP for sub-second accuracy.

Will DST changes update automatically?

Yes. The displayed offset follows the IANA rules built into the browser, so when a zone enters or leaves DST the clock shifts at the rule's transition instant.

Can I share my list of zones?

Your selection is stored in the URL as a query parameter, so copying the address bar shares the exact zone set.

No. The time, zone offsets, and DST rules all come from the browser; no network calls.

ticking · multi-zone · IANA · live

Live world clock across timezones

Pick the cities you care about. Each clock ticks once per second with full DST awareness, current weekday, and UTC offset.

Quick Start

How the world clock works

Each row is rendered with Intl.DateTimeFormat for its timezone. A 1-second interval triggers a re-render so the seconds tick visibly.

01
Pick defaults
Six common zones load by default — Tokyo, Kolkata, London, NYC, LA, Sydney.
Parsing accepts ISO 8601, RFC 3339, RFC 2822, and Unix epoch seconds/milliseconds. The Date constructor handles the rest with browser-engine consistency.
presetISO 8601RFC 3339epochlive
init · timestamp6 zones · ISO
```
Tokyo, NYC, …
```
loaded · ISO 8601zone · ready
02
Add a city
Pick from the IANA list — any continent.
All math runs in UTC internally to avoid DST landmines; presentation converts back to the user’s zone via Intl.DateTimeFormat.
addUTC mathIntlDST-safelive
select · optionsIANA · live
```
Europe/Berlin
```
options applied · UTCDST-safe
03
Remove a card
Click the ✕ on any chip to remove it.
Output respects the chosen timezone offset (Z vs +05:30) and pads digits per ISO conventions so sorts stay chronological.
removeoffsetzone-awaresortablepadded
✕ · computedchip · ready
```
removed
```
computed · instantsortable
04
Copy all
One click puts every zone+time on the clipboard.
Copy writes via the Async Clipboard API; nothing pings a time server — the browser’s clock is the only oracle.
copyclipboardno oracledeterministicclient-side
✓ · copiedready · done
```
✓ Copied
```
shipped · ready to shipsuccess

Pro tips

Time math without DST landmines

Always store UTC

Convert to local for display only. UTC storage avoids DST jumps and timezone drift in databases.

Watch leap seconds

POSIX time doesn’t count leap seconds; some systems do. Don’t use timestamps for sub-second precision across boundaries.

Prefer Temporal eventually

The Date API has many quirks. Temporal is shipping in modern engines and handles zones correctly.

Cron is timezone-tricky

Cron expressions run in the daemon’s local zone unless told otherwise. Pin a TZ explicitly for predictable runs.

ISO 8601 sorts naturally

YYYY-MM-DDTHH:mm:ss sorts correctly as a string. Don’t use US-style MM/DD/YYYY for anything machine-readable.

Beware Y2K38

Signed 32-bit Unix timestamps overflow in 2038. Use 64-bit storage end-to-end for long-lived systems.

Use Cases

When to glance world time

Remote teams, sales, travel.

Remote standups

See if a teammate is awake before paging them. Math runs in UTC under the hood to dodge DST jumps — local time is only for display. That means scheduling logic and date diffs survive March / November fall-back without the classic off-by-one-hour bug.

DST-safe

Sales calls

Quick check before dialling a prospect. Browser clock is the only source — no external time server, no privacy leak, no rate limit. Pair with NTP-synced server time for high-accuracy use cases, but for human-scale work the browser clock is plenty.

UTC-correct

On-call rotations

Confirm who's in-hours globally. ISO 8601 output sorts naturally as strings, perfect for filenames (report-2026-01-15.pdf) and log lines that need chronological ordering without parsing. Drop into S3 keys for free time-bucketing.

ISO-sortable

Release windows

Plan deploys around active user regions. Pairs cleanly with cron, scheduled tasks, and timestamped log analysis. The tool's output drops directly into APScheduler, Linux cron, or GitHub Actions schedule expressions without re-formatting.

spec-grade

Travel days

Mental rehearsal of arrival times. Output respects the chosen timezone offset (Z vs +05:30) so REST APIs and database TIMESTAMP WITH TIME ZONE columns round-trip cleanly. No ambiguity between "noon UTC" and "noon local".

zone-aware

Family abroad

Don't call grandma at 3am. Confirms the difference between epoch seconds (10 digits) and milliseconds (13 digits) before you commit code that mis-multiplies by 1000 — a classic bug in cross-language time handling.

epoch-accurate

FAQ

Frequently asked questions

Is the time accurate?

It's your browser clock applied to each zone. Sync your OS clock for sub-second accuracy.

Does DST work?

Yes — the zone IDs trigger DST transitions automatically via Intl.

Why a 1-second interval?

Smooth enough to read seconds ticking without burning CPU.

Can I save my zones?

Not yet — refresh to start from defaults.

Is anything sent to a server?

No. All clocks come from your browser.

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