# Best Online Clock: product facts and limitations

Canonical site: https://bestonlineclock.com/

Best Online Clock is a collection of interactive browser tools. It does not require an account or software installation. The descriptions below reflect implemented behavior and should not be interpreted as medical, sleep, safety, or professional timing advice.

## Clock

URL: https://bestonlineclock.com/

- Reads the device's system time and aligns display updates to system-second boundaries.
- Supports 12-hour or 24-hour time, optional seconds, date, weekday, and week number.
- Supports font, size, color, position, and background settings stored locally in the browser.
- Fullscreen can request Screen Wake Lock on supported browsers and devices.

## Timer

URL: https://bestonlineclock.com/timer

- Accepts a duration up to 99:59:59 or a future target date and time.
- Supports start, pause, resume, reset, and completion state.
- Uses a deadline-based countdown so the display can recover after delayed browser updates.
- Includes 27 selectable alert sounds with an explicit preview control.
- Provides 24 interactive preset routes from 1 minute through 8 hours.

Keep the page open until completion. Test the sound first because browsers, permissions, muted devices, background restrictions, and power state can affect playback.

## Alarm

URL: https://bestonlineclock.com/alarm

- Supports multiple locally stored alarms with a time, label, sound, and enabled state.
- Prevents duplicate permanent alarms for the same time on one page.
- Provides sound preview, notification-permission status, missed/recovered status, and a queue for due alarms.
- Permanent alarms repeat daily. Snooze creates a temporary follow-up alarm for 1, 5, or 10 minutes.
- Provides 33 preset alarm-time routes.

Keep the tab open while an alarm is scheduled. Test audio and review the displayed reliability status. The application does not claim that a browser alarm can replace a device alarm or safety-critical reminder.

## Stopwatch

URL: https://bestonlineclock.com/stopwatch

- Measures elapsed time from the browser's monotonic performance clock.
- Supports start, pause, resume, reset, and lap records.
- Offers millisecond, centisecond, decisecond, and second-only display formats.
- Exports the current session and lap data as CSV.

Practical display precision depends on the browser, device, rendering schedule, and power state.

## World time

URL: https://bestonlineclock.com/time

- Includes 57 cities backed by IANA time-zone identifiers.
- Displays a selected city's current date, time, UTC offset data, and city information.
- Supports comparing up to five selected cities with the local clock.
- Daylight-saving behavior comes from the browser's time-zone implementation.

City routes are listed in https://bestonlineclock.com/sitemap.xml.

## Fullscreen and Wake Lock

Fullscreen changes the presentation of a tool. Where the Screen Wake Lock API is available, the site can request Wake Lock and display its current status. A request can be unsupported, denied, interrupted, or released. Fullscreen and Wake Lock do not guarantee alarm delivery, audio playback, background execution, or that a device remains awake.

## Storage and analytics

- User-created tool settings and alarm data are stored in the current browser's local storage or IndexedDB, depending on the feature.
- Uploaded background assets stay in browser storage unless the user supplies an external image URL.
- No account is required.
- On canonical production only, Google Analytics is delayed until interaction or a visible long-stay fallback.
- Microsoft Clarity is limited to a sampled set of sessions and is also delayed.
- Coarse Web Vitals diagnostics are sampled and exclude raw text, full URLs, query strings, referrers, and DOM content.
- Advertising is loaded separately after its existing delay boundary.

The current details and data boundaries are documented in the [Privacy Policy](https://bestonlineclock.com/privacy-policy).

## Canonical resources

- Home: https://bestonlineclock.com/
- About: https://bestonlineclock.com/about
- Testing methodology: https://bestonlineclock.com/methodology
- Timer: https://bestonlineclock.com/timer
- Alarm: https://bestonlineclock.com/alarm
- Stopwatch: https://bestonlineclock.com/stopwatch
- World time: https://bestonlineclock.com/time
- Privacy: https://bestonlineclock.com/privacy-policy
- Terms: https://bestonlineclock.com/terms-of-service
- Contact: https://bestonlineclock.com/contact
- Sitemap: https://bestonlineclock.com/sitemap.xml