A countdown timer where the whole timer lives in the link. You fill out a short form, get a URL, and share it. Anyone who opens it sees a live countdown. No account, no sign-up, no database.

Open this page with no # in the URL and you get the builder: an event title, a target date and time, which units to show (days/hours/minutes/seconds), and what happens at zero. Hit Generate link, then Copy link.

Paste the copied link anywhere — chat, email, a calendar invite. Opening the link is the timer; there’s nothing to install.

You get the builder back with an inline message explaining what was wrong (bad timestamp, bad units, bad zero-behavior) rather than a blank page or an error. Nothing crashes.

• Stop at zero — freezes at 00 and shows a “✓ Title has arrived.” banner.
• Count up — past the target it keeps going, showing elapsed time in red.

Yes. Your date and time are entered in your local timezone, but the link stores an absolute UTC instant. Everyone who opens it counts down to the exact same moment, whatever their timezone.

No. Every tick recomputes from the current wall clock rather than subtracting one second from a counter, so it self-corrects after sleep/wake and after browsers throttle background tabs.

When the tab is in the background, the tab title shows the running clock (e.g. 02d:14h — Launch Day, or +00m:42s when counting up) so you can watch it from another tab. Focus the tab and the title goes back to just the event name.

Not in place — the link is the timer. Make a new one and share the new link. The old link keeps working until people stop using it.

No. Settings go after the # in the URL, and browsers never send that fragment to the server. A host serving this file sees only GET /index.html — never your title or date.

No cookies, no localStorage, no sessionStorage, no IndexedDB.

None at runtime. No CDN scripts, web fonts, analytics, or remote images — even the hourglass favicon is inlined. A Content-Security-Policy blocks outbound requests at the browser level, so it’s enforced, not just promised.

No.

Yes. Save this page as a single index.html and open it via file:// — builder and viewer both work with no internet.

Almost — three things are outside this page’s control and worth knowing:

• Browser history. The full URL, title and all, lands in local history like any URL. If browser sync is on, it syncs to the vendor and your other devices, and it shows up in address-bar autocomplete on shared machines.
• Clipboard managers. “Copy link” writes plain text to the OS clipboard; any clipboard-history tool retains it.
• Access logs. If hosted, the host logs that a request happened (IP, time, user agent) — never what the countdown is about.

No. It’s readable by anyone who has it — treat it like an unlisted link, not a password-protected one.

The toggle in the top-right cycles auto → light → dark for the current session only. Persisting it would require storage, which this page deliberately never uses, so it resets to auto on reload. Auto follows your operating system’s setting.

Yes — pick any combination under “Units to display.” Whatever you leave out gets rolled into the largest unit shown (turn days off and hours accumulate past 24, and so on). Display order is always days → hours → minutes → seconds regardless of how you check them.

Yes — the layout scales fluidly and the number boxes wrap on narrow screens.

Yes. It’s one self-contained HTML file, MIT-licensed, with no build step. Drop it on any static host. Include the _headers file on Cloudflare Pages or Netlify to also get the CSP, HSTS, and anti-clickjacking headers.