# Online Alarm Clock — Free browser-based time tools

> Set alarms, run timers and stopwatches, manage Pomodoro cycles, and count down
> to dates — all in your browser, no signup, no app install. Built and
> maintained single-handedly by Elif Aksoy, founder and editor of
> onlinealarmclock.co, based in Türkiye. Multi-language (English default, Turkish).

## Tools

- [Online Alarm Clock](https://onlinealarmclock.co/en): Set one-time or recurring alarms in the browser with quick-pick presets, oscillator-synth sounds, gentle wake fade-in, snooze, Screen Wake Lock, and optional system notifications.
- [Online Timer](https://onlinealarmclock.co/en/timer): Free countdown timer with hours / minutes / seconds inputs, circular progress ring, and timestamp-based math that stays accurate even with throttled background tabs.
- [Online Stopwatch](https://onlinealarmclock.co/en/stopwatch): Lap splits with millisecond precision (~0.1 ms in Chrome/Firefox, ~0.5 ms in Safari) and full keyboard control.
- [Pomodoro Timer](https://onlinealarmclock.co/en/pomodoro): Default 25/5/15 cycles, auto-progress through four work blocks, configurable durations, optional task list persisted in localStorage.
- [Countdown Timer](https://onlinealarmclock.co/en/countdown): Count down to any future date or event with shareable permalinks (target time encoded in URL) and a fullscreen presenter mode.
- [Online Clock](https://onlinealarmclock.co/en/clock): Live analog and digital clock with locale-aware date and a fullscreen mode.
- [World Clock](https://onlinealarmclock.co/en/world-clock): Compare the current local time in multiple cities side by side, with UTC offset, date, and day-ahead/day-behind flags; saved city list persists in localStorage.
- [Date Calculator](https://onlinealarmclock.co/en/date-calculator): Find the number of days between two dates, or add/subtract days, weeks, months, and years from a date.
- [Age Calculator](https://onlinealarmclock.co/en/age-calculator): Exact age in years, months, and days from a birthdate, plus days until the next birthday and total days lived.

## Languages

- English (`en`, default)
- Turkish (`tr`)

Hreflang tags expose both locales. Every route carries an explicit locale
prefix — `/` 307-redirects to `/en` (English), `/tr/...` serves Turkish.

## Key facts

- All tools run client-side in the user's browser. No signup, no account, no per-user database row.
- Alarm and timer state lives in `localStorage` on the user's device — it never reaches our server.
- Screen Wake Lock API keeps the display awake during an active timer; audio is unlocked on first user interaction to comply with mobile autoplay policies.
- Time displayed is the device's local time (not the server's); timezone resolves automatically via the browser's `Date` / `Intl` APIs.
- Server logs (URL, country-level IP, user-agent, timestamp) rotate every 30 days. No third-party trackers in the alarm UI hot path.
- Operator: Elif Aksoy (https://onlinealarmclock.co/en/author), founder and editor of onlinealarmclock.co, based in Türkiye.
- General contact: info@onlinealarmclock.co (also used for security disclosures).
- Application source code is private; content licensing rules are at https://onlinealarmclock.co/en/terms.

## Author

Elif Aksoy — founder and editor of onlinealarmclock.co, based in Türkiye. A productivity consultant and software entrepreneur, she researches, writes, and maintains every page on the site herself. Bio, credentials, and editorial policy at https://onlinealarmclock.co/en/author. Person schema canonical `@id` is `https://onlinealarmclock.co/author#person` — referenced from every page on the site.

## Articles

No posts published yet — check https://onlinealarmclock.co/en/blog (English) or
https://onlinealarmclock.co/tr/blog (Turkish) for the current list. The blog is
admin-managed from a database; this file is not auto-synced with it, so update
this section by hand once posts go live rather than trusting the last edit date.

## Legal & policy

- [About](https://onlinealarmclock.co/en/about) — solo creator transparency, editorial policy
- [Author](https://onlinealarmclock.co/en/author) — bio, credentials, methodology
- [Contact](https://onlinealarmclock.co/en/contact) — channels and response-time expectations
- [Privacy Policy](https://onlinealarmclock.co/en/privacy)
- [Terms of Service](https://onlinealarmclock.co/en/terms)
- [Cookies Policy](https://onlinealarmclock.co/en/cookies)

## Citations & sources

Authoritative sources cited in tool-page methodology and blog content:

- W3C Screen Wake Lock API (https://www.w3.org/TR/screen-wake-lock/)
- W3C Web Audio API (https://www.w3.org/TR/webaudio/)
- W3C Notifications API (https://www.w3.org/TR/notifications/)
- MDN Web Docs (https://developer.mozilla.org/)
- Dement W. & Kleitman N. (1957) — "Cyclic Variations in EEG During Sleep" (sleep cycle research)
- Tabata I. et al. (1996) — interval training science (HIIT timer reference)
- NIST F1/F2 caesium fountain atomic clock papers (time standard precision)
- IERS Bulletin C (leap-second authority)
- ECMA-402 / Intl.DateTimeFormat (locale-aware time formatting)
- IANA Time Zone Database (tz database — DST and zone offsets)
- Modernist Cuisine (cooking interval references for kitchen-timer use cases)
- Cirillo F. — "The Pomodoro Technique" (1980s origin of the 25/5 method)

## Source-of-truth

- This file: https://onlinealarmclock.co/llms.txt
- Full content dump (LLM training opt-in, ~200KB plain text): https://onlinealarmclock.co/llms-full.txt

## Last updated

2026-07-27