How it works : Timer
A timer that counts what is left from a fixed end instant, never by adding up ticks: that is the only way not to drift when the browser slows its timers down, which it does to save power and documents openly.
Searching for “online timer” returns pages drowning in adverts, loading dozens of tracking scripts in order to display four digits. It is absurd: a countdown is the simplest program a browser can run, and it needs nothing beyond your own device's clock.
This one does not drift, and that is the technical point that matters. A naively written timer adds up one-second ticks; but browsers deliberately slow their timers down when a tab goes into the background, as far as one tick a minute, and they document it. A timer counting ticks then loses whole minutes. This one holds an END INSTANT on the browser's monotonic clock and works out what is left on every frame: background or not, the finish time is the same.
One thing has to be said straight away: this is not a display for a projector. The digits on this site go up to a certain size and no further, and building a giant display would need a graphical component we do not have. The fullscreen mode exists, but it enlarges the surface, not the digits. That is written here rather than discovered in front of a class.
How it works
- Choose a plain timer or work cycles, set the duration, then start it.
- The tool shows the time left and rings at the end. The bell is built by the browser: no sound file is downloaded.
- During cycles, the tool moves between work and break on its own, and rings at every change of phase.
Formats accepted
This tool takes neither a file nor a text. All it needs is your device's clock, and it writes nothing: not on a server, not on your machine. Closing the tab erases everything, settings included.
No input
The tool starts from your settings and the browser's monotonic clock. It works with the connection cut, and it never had anything to load in order to work.
Its limits
This is not a projector display, and the fullscreen mode does not enlarge the digits
This site's design system has a maximum digit size, and a giant display would be a new component. We do not knock a component together: the design is frozen, and what is missing gets noted rather than invented. Fullscreen mode only fills the screen with the same display. If a real classroom display is what you need, that is a fair request, and it is already noted.
We do not use the name of the best-known work method, and here is why
The method of twenty-five-minute cycles followed by five-minute breaks was proposed by Francesco Cirillo, and its Italian name has been registered as a trademark. Checking the registers, we found that the American registration of the bare word was CANCELLED in February 2025 for want of a maintenance declaration, that two fresh applications from the same filer are under examination without being registered, and that we cannot verify the European position from a first-hand source. The rights holder, however, publishes guidelines requiring formal permission for any use, with no exception for free tools. In doubt, we describe the method and name its author, without using his trademark as the name of a mode in our tool. This is neither an affiliation nor a challenge: it is what we were able to verify, written as we found it.
In a background tab the display updates slowly, but the finish time stays right
Browsers deliberately throttle the timers of a hidden tab to save battery, and it is documented: the most widely used one drops to one check a minute after five minutes out of sight, another caps at one a second on desktop and may unload the tab entirely on a phone after a quarter of an hour. Our arithmetic rests on an end instant, so it always catches up at the next frame. But if the system unloads the tab, the bell will not ring: keep the tab visible for a timer that really counts.
The screen is kept awake where the browser allows it, and the lock is lost in the background
The feature that stops the screen going dark exists in every modern browser, but it requires a VISIBLE page: the specification has the lock released as soon as the tab goes into the background, and the tool asks for it again on your return. On iPhone it only worked inside an installed app from March 2025 onwards. When it is refused, the tool says so rather than letting you believe the screen will stay lit.
Fullscreen does not exist at all on iPhone
This is not a limit of our tool: Apple's browser on iPhone cannot put a page element into fullscreen, only a video. The request was opened on their side in 2020 and it is still open, checked as far as the release notes of the version being prepared in the summer of 2026. On iPad, by contrast, it has worked since 2023. So the tool detects the feature and hides the button when it is absent, rather than offering a button that does nothing.
Nothing is remembered from one visit to the next
No local storage key is written, so the timer returns to its default value every time it opens. That is the site's rule, and for a timer it costs three seconds of setting up.
Questions about this tool
Are there adverts or tracking on this page?
None, and you can check it in ten seconds, which is the opposite of what you will find on most online timers. Open the inspector with the F12 key, go to the “Network” tab, clear the list, then start the timer: the list stays empty. Cut your connection and the page keeps counting.
Why does the timer not drift when I switch tabs?
Because it does not count seconds, it looks at the clock. On starting, it works out an end instant on the browser's so-called monotonic clock, the one the standard guarantees never runs backwards, even if the system adjusts its time. Then, on every screen refresh, it does one subtraction. A timer adding one second per tick would be at the mercy of background timer throttling, which browsers apply deliberately: as far as one tick a minute. On a twenty-five-minute timer left in the background, the consequence is measured in lost minutes.
Will the bell ring if I leave the tab in the background?
Usually yes, with a possible delay of a few dozen seconds, because the tool can only ring at the moment the browser hands control back to it. But there is one case where it will not ring at all: when the system unloads the tab entirely to free memory, which mobile browsers do after roughly a quarter of an hour. For a timer an activity depends on, keep the page visible: that is also what lets the screen stay lit.
Why does fullscreen mode not enlarge the digits?
Because digit size belongs to this site's design system, which is frozen, and its largest digit size was not drawn to be read from the back of a room. Building a giant display would mean adding a graphical component, and the rule here is plain: what is missing gets noted and requested, it does not get invented in the middle of a tool. Fullscreen is still useful for taking the rest of the page out of view; it does not replace a classroom display, and we would rather write that than let you find out in front of your pupils.
Why do you not say the name of the twenty-five-minute method?
Out of caution, and it is better said plainly than left vague. The Italian name of that method was registered as a trademark by its author, Francesco Cirillo, who publishes guidelines requiring formal permission for any use, with no exception for free tools. Checking the registers, we found that the American registration of the bare word was cancelled in early 2025 for want of a maintenance declaration, that two fresh applications are under examination, and that the European position is not verifiable by us from a first-hand source. So we settle no legal question: we name the author, we describe the durations, and we do not use his trademark as the name of a mode in our tool.
Can I use it as a stopwatch, counting upwards?
No, this tool only counts down, and adding a stopwatch is not a settled decision. A countdown and a stopwatch have different displays, different controls and different uses, and mixing them into one page would end up hindering both. If the need is real, say so: the way this site grows is by a missing tool being asked for, not by it being bolted on as an option of another one.
Are my settings kept for next time?
No. This site writes only the display preferences you explicitly ask for in its panel, and nothing else: no timer duration, no session history. You lose three seconds of setting up every time it opens, and in exchange no record of your working hours exists anywhere.
A timer that counts what is left from a fixed end instant, never by adding up ticks: that is the only way not to drift when the browser slows its timers down, which it does to save power and documents openly.
VerifyThe proof, step by stepThe network inspector check, explained one gesture at a time, with screenshots.
The cornerThe classroom cornerFor people who teach: a timer with its work cycles, a random draw that does not cheat, worksheets as PDF, and flashcards whose schedule stays inside your own file.