Countdown / count-up timer — time left or elapsed until target date
Real-time display of the remaining time until (countdown) or the elapsed time since (count-up) a target date. Days / hours / minutes / seconds tick every second. Copy the URL to share the current setup (?to=datetime&mode=countdown). Uses your browser's local timezone. Runs entirely in your browser — the target datetime never leaves your device.
How to use
Pick a target datetime (datetime-local input) and toggle the direction (countdown / count-up). The result updates every second. Click 'Copy share URL' to get a URL with the current target and direction (e.g. `?to=2026-12-31T23:59&mode=countdown`) — handy for bookmarks or sharing across devices. The target datetime is interpreted in your browser's local timezone and never leaves your device.
FAQ
- Is the target datetime uploaded?
- No. It's only kept in the URL query and in the page's state — no server contact. Even if you share the URL, the recipient processes it entirely in their browser.
- How is the timezone handled?
- We use your **browser's local timezone**. For example, `2026-12-31T23:59` typed on a JST browser means 23:59 JST. If you need cross-timezone sharing, compute the UTC offset before entering the time (a TZ picker may come later).
- What does the share URL contain?
- Just the target datetime (`?to=YYYY-MM-DDTHH:MM`) and the direction (`?mode=countdown` or `countup`). Opening the URL starts the same display in another browser.
- What happens when a countdown reaches zero?
- It shows 'Finished' and stays at 0 (no negative values). If you want to keep tracking time after the moment, switch the direction to 'Count-up'.
- Does it keep running when the page is closed?
- There's no internal timer that 'runs' — the display is just the current time vs. the target datetime, computed when the page is open. Open it any time later and the remaining / elapsed time is correct.
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