Paused time stays excluded. Running time away is recovered with a stated basis, and browser sound is never an asleep-alarm guarantee.
Set this session; prepare the next one
Enter a duration from one second to 24 hours, such as 25 min, 90s or 01:30:00. Start begins the countdown, Pause captures progress, and Resume continues without adding time spent paused. The display derives elapsed time from a monotonic reference; a late repaint catches up rather than losing seconds.
Changing the duration or choosing a preset prepares the next session. It does not replace a running or paused timer. Reset asks for confirmation before discarding progress. The timer keeps running while that confirmation is open, and cancelling keeps the session.
What happens after reload or returning
The countdown saves checkpoints in local browser storage, including elapsed progress, its running or paused state, and next-session settings. A paused timer stays paused after reload. A running timer includes time away, and a completed timer returns as completed rather than starting again.
Recovery compares synchronized UTC only when both checkpoints have trusted recent UTC. Otherwise it estimates from the device clock and shows uncertainty. A clock moving backwards keeps saved progress and warns that time away could not be measured reliably. A later trusted refresh can improve the result, but cannot overwrite a newer control action or input edit.
Saved progress has one current owner
The most recently opened or controlled timer tab writes saved updates; other open tabs follow them. A saved Reset clears progress across those tabs, and an old tab leaving the page cannot overwrite a newer reset with its stale session. If a change arrived before your action, the page restores the newer state and asks you to review it before acting again.
Storage is not permanent backup. Clearing site data removes saved sessions, and private browsing, storage limits or browser settings may prevent saving. The storage notice tells you when keeping this page open is necessary. Unknown saved formats are left untouched until an explicit new session or reset.
Test sound before relying on it
Sound starts off. Select it and use Start, Resume or Test sound to enable audio through a user action. A reload does not automatically regain audio permission. Test sound requests a short gentle sequence, but the browser cannot prove that your speakers are connected or your device is unmuted.
Blocked, suspended or failed audio leaves completion visible. A provisional completion based on uncertain recovered device time skips an automatic tone; if a trusted refresh is pending, sound waits for that result. A correction back to running keeps the actual deadline eligible for its completion sequence. The page explains the outcome beside the sound controls.
Keep a suitable separate alarm for an important reminder. An ordinary browser page cannot guarantee a sound while the device is asleep, the browser is closed or the operating system has suspended it.