About Digital Clock Online

Digital Clock Online is a clock that checks itself. Most clock pages read whatever time your device reports and display it, so a wrong device means a wrong page, shown with complete confidence. This one asks a server what time it is and tells you when the two disagree.

How the clock works

When the page loads, your browser requests a timestamp from this site's server. That request is not cached, so it cannot come back stale. The browser measures how long the round trip took and uses half of it to estimate what the server time was at the moment the answer arrived.

The browser applies the measured difference as an offset, then advances the display locally from that server-derived starting point. It refreshes the measurement periodically and when you return to the tab.

If your device is off by enough to matter, a warning appears with the measured difference. The display remains synchronized; the warning tells you that the system clock itself needs attention. If the server is temporarily unavailable before any measurement succeeds, the page labels its device-time fallback and retries.

What it cannot do

A clock in a web browser cannot be more accurate than the network it runs on. The round trip to the server sets the limit, usually well under a second but never zero. If you need better than that, you need hardware built for it, not a web page.

The site does not set your device clock. It can show synchronized time and tell you the device is wrong; changing the system setting is something only your operating system can do.

The clock does not run in the background. Close the tab and nothing keeps counting.

Where the time zone data comes from

Every country and time zone page on this site is generated from published sources, not typed by hand and not copied from another clock site.

• Time zone rules come from the IANA Time Zone Database, release 2026c, published 8 July 2026. This is the same database operating systems use for their own time zone handling.
• Place names and territory assignments come from Unicode CLDR 48, with Unicode 16.0.0.
• Country codes follow ISO 3166.

That produces 247 country pages and 312 time zone pages.

Time zone rules change. Governments move transition dates, add offsets and abolish daylight saving with little notice, and when the IANA database publishes a change, this site is rebuilt from it. Where a zone has no official abbreviation in the source data, the pages leave that field blank rather than printing a generated substitute like "GMT+9" as though it were a real name.

Browser extension

The Digital Clock Online browser extension replaces the new-tab page with a flip clock. Its core clock and appearance settings work without a Google account. Clock settings use Chrome or Firefox profile sync by default, while saved playlists stay on the device.

You can separately connect read-only YouTube access for playlist browsing and playback, play a radio stream you provide, or enable Google Drive App Data sync for clock settings and saved playlist records. Google features remain off until you choose them. The Extension does not collect usage analytics.

How the Website and Extension handle information is explained in the Privacy Policy. Use of both products is covered by the Terms of Use.

Getting in touch

Corrections to time zone data are the most useful thing you can send. If a page shows the wrong offset, the wrong abbreviation or a transition that did not happen, tell me which page and what it should say, through the contact page. Data corrections are checked against the IANA source and fixed at the generator, so one report fixes every page that shares the fault.