Privacy Policy
World Time Lab is a static site with no accounts and no server-side application code. Almost everything you see is computed in your own browser. This page says precisely what that means, and is honest about the parts that are not local.
Last reviewed July 21, 2026Site version v2026.7.5This build loads no third-party scripts
The short version
- No account, no login, no password, no email address is ever requested.
- Nothing here asks for your location on its own. One feature can ask, and only if you press a button: Use my locationin the eclipse tool. What your browser returns is used in the page and saved in the page's own storage. It is not sent anywhere and is not written into the address bar.
- Your device time zone, which is a much coarser thing than a position, is read on most pages to label your own clock. It never leaves your device either.
- Time zone, solar, lunar, eclipse, calendar, date, distance, simulator, timer and stopwatch calculations all run in your browser. Your inputs are not transmitted.
- The site has no contact form and no server that could receive one.
- This build loads no third-party scripts, no third-party fonts, no embedded videos, and no tracking pixels of any kind.
What runs on your device
World Time Lab is exported as static files. There is no application server, no database, and no place for your input to be stored even if it were sent. When you use a tool here, the arithmetic happens in the page you already downloaded:
- Clocks and time zone conversion. The page asks your browser for its own IANA time zone database and formats times from it. Your device time zone is read locally to show relative labels such as today and tomorrow; that value is never sent anywhere.
- Sun, twilight, moon, seasons. Standard published equations evaluated in JavaScript on the coordinates of the place you chose.
- Eclipses and holidays. Static tables shipped with the page, filtered in the browser.
- Date calculators, countdowns, calendars, the printable calendar maker, distance, Planet Lab, the timer, the stopwatch and the reaction-time test. All entirely local, including the values you type into them.
What goes in the address bar, and what does not. Planet Lab writes your planet settings into the address bar as the p and s parameters, using the browser history API. Those are invented planets, not facts about you. The rewrite happens on your device and sends nothing by itself. It exists so a planet can be bookmarked or shared, and if you do share that link, the settings travel inside it.
Places you pick are treated differently. The eclipse tool and the Moon tool never put your chosen place, its coordinates or its time zone into the address bar. A URL is not a private thing to hold a position in: it is sent to other sites in the referrer header, it is kept in browser history and in whatever syncs that history, and it is readable by any advertising or analytics script a page loads. Both tools keep the place in the page instead, and each has a copy-link button that builds a shareable link only when you press it. Each button is next to a sentence saying that the link it produces contains the place.
The meeting planner is the exception, and it is deliberate. It does write your pinned locations, their time zones, the date and the selected time into the address bar as you work, using the same history API. That is what makes a plan bookmarkable and sendable, which is most of the point of the tool. It matters that you know two things about it. The labels are exactly what you typed, so if you rename a clock to something personal, that text is in the URL. And everything in the paragraph above about where a URL travels applies here too. If you would rather it did not, use the converter on the home page, which keeps its clocks in the page and in your browser only.
A link someone sends you still works. Coordinates, labels and dates that arrive in a URL are range-checked, clamped and stripped of control characters before anything is drawn from them, and anything unusable is discarded rather than half-applied.
Location permission, in full.One control on this site can trigger your browser's location prompt: the Use my location button in the eclipse local-circumstances tool, which exists so you do not have to type coordinates to find out whether an eclipse reaches you. It runs only from that press. It is not called when a page loads, not on a timer, and not as a fallback when something else fails, so you will never see a location prompt you did not ask for.
If you allow it, the coordinates your browser reports are rounded, used to compute contact times in the page, and saved under the sd-eclipse-place key described below so the tool opens there next time. They are not transmitted: this site has no server that could receive them. If you refuse, the tool says so plainly and you can search for a place or type coordinates instead. Nothing is withheld from you for refusing.
Every other capability of that kind is switched off at the server response header, and the geolocation permission itself is granted only to this site's own pages, never to a third-party frame inside them.
What leaves your device
Requests to the host
Loading any web page means asking a server for files. Whoever hosts World Time Lab therefore receives what every web server receives: the IP address making the request, the time, the path requested, your browser's user agent string, and a referring page if your browser sends one. World Time Lab's own code adds nothing to those requests, sets no identifier, and does not read them back.
The operator of World Time Lab does not operate the network layer beyond configuring the host, and the retention period for standard access logs is set by that host rather than by this site. If you need that specific detail, ask through the contact page.
Data files fetched on demand
Some features need a data file that is too large to ship with every page, so it is fetched only when the feature is used. These are plain static files from the same host as the page. They contain no identifiers and set no cookies, but the request for them appears in the host's normal log in the same way a page request does.
| File | Size | Fetched | Contents |
|---|---|---|---|
/map/world-110m.json | 105 KB | On the first load of the globe. | Country outlines for the map. |
/map/tz-regions.json | 150 KB | When you first select a country that uses more than one time zone. | Time zone boundary polygons, so each zone can be shaded separately. |
/map/climate.json | 42 KB | When you first switch the globe to the Seasons view. | A coarse climate grid used to color the world by season. |
/map/admin1/<country>.json | varies | When you select a country. | State and province boundary lines for that one country. |
/map/admin1-regions/<country>.json | varies | When you hover or tap inside a country long enough to ask for detail. | Named first-level regions, so the map can say Texas rather than United States. |
/data/cities/<prefix>.json | small shards | When you type at least two characters into city search. | Only the shards matching the first two letters of each word in your query are downloaded, at most four. |
City search is the one worth spelling out. Your query is not sent to a search service. The browser normalizes your query, splits it into words, and downloads the shard for the first two letters of each word, up to four shards, and matches inside the page. The host can see which shard was requested, which is a much coarser signal than the query itself, and typing more characters never triggers another request for that prefix.
Third-party services
This build loads no third-party scripts at all. No advertising, no analytics, no tag manager, no social embeds, no hosted fonts, no content delivery network beyond the host serving these files. Nothing on a World Time Lab page contacts another company on your behalf.
Advertising and analytics are configuration, not code that is always present: they are switched on only by supplying credentials at build time. When that happens, this page changes with the build to describe exactly what was enabled, and the cookie policy gains the matching cookie list. If you are reading this sentence, neither was enabled for the build you are looking at.
Storage on your device
World Time Lab uses your browser's local storage for preferences. Local storage is not a cookie: it is never attached to a network request, so these values do not travel to the host or to anyone else. They stay in your browser until you clear site data.
sd-theme- Holds: The single word "light" or "dark".
- Written: When you press the light and dark toggle in the header.
- Why: So the page opens in your chosen theme instead of flashing the wrong one.
sd-pinned-places-v2- Holds: The places you pinned: display name, country code, time zone id, coordinates, and the time you pinned each one.
- Written: When you pin, re-pin, or remove a place in the world clock workspace.
- Why: So your pinned clocks are still there when you come back.
sd-pinned-places-v1- Holds: An older version of the same pin list.
- Written: Never. It is read once, on first load, if it already exists.
- Why: So pins created before the format changed are not silently lost.
sd-calendar-maker-project- Holds: Your calendar draft: title, year, layout, colors, chosen holiday sets, personal dates, and a logo if you added one.
- Written: While you work in the printable calendar maker.
- Why: So a long piece of work survives a reload or a closed tab. Nothing in it is uploaded.
sd-timer-presets-v1- Holds: The durations and labels you saved.
- Written: When you save a timer preset.
- Why: So your own presets are there next time instead of being retyped.
sd-reaction-history-v1- Holds: Your recent session times and your best result.
- Written: When you finish a round of the reaction-time test.
- Why: So the test can show your progress. It is scoring you against yourself, not against anyone else.
sd-hour-cycle-v1- Holds: The single word "h12" or "h23".
- Written: When you pick 12-hour or 24-hour in the clock format control. Choosing to follow your browser again deletes it.
- Why: So every clock on the site keeps the format you chose, on every page and on every visit.
sd-eclipse-place- Holds: That one place: its label, its latitude and longitude rounded to four decimal places, and its time zone id.
- Written: When you choose a place in the eclipse local-circumstances tool: by searching for it, by typing coordinates, or by pressing Use my location.
- Why: So the eclipse pages open on the place you last asked about instead of making you find it again. It is written to your browser only. It is not sent anywhere, and it is not put in the address bar.
Those are the keys this build writes, and each one is only created once you use the feature that needs it. Every key carries the sd-prefix, so you can confirm the current set for yourself in your browser's storage panel rather than taking this page on trust.
To remove them, clear site data for this domain in your browser settings, or visit in a private window, where they are discarded when you close it. Blocking storage does not break anything: the theme falls back to your system preference, and pins, presets and drafts simply last for the session instead.
Because this build has no third-party scripts, nothing else writes to your browser: no cookies are set at all. The cookie policy covers this in more detail.
Retention
World Time Lab keeps no database and no user records, so there is nothing here to retain. The only persistence is on your own device, in the keys listed above, and it lasts exactly as long as you leave it there.
Where third-party services are enabled for a build, their retention is governed by their own policies rather than by this one, and their documentation is linked above.
Children
World Time Lab is a general-audience reference site and is often used for homework. It does not knowingly collect personal information from anyone, including children, because it does not collect personal information at all: there is no registration, no profile, no upload, and no message feature.
With no advertising or analytics in this build, there is also no third-party profiling to be concerned about. A parent or guardian with a question can write through the contact page.
Your choices and your rights
Depending on where you live, data protection law may give you rights to access, correct, delete, restrict, or object to the processing of personal data about you, to withdraw consent, and to complain to a supervisory authority. Those rights apply to whoever holds data about you.
In World Time Lab's case the honest answer is that there is almost nothing to exercise them against: no account exists, no profile is built, and no personal data is stored by the site. Requests about the standard server logs of the host, or about a third-party service enabled in a given build, are best directed to that host or that provider, and the operator of World Time Lab will point you to the right place if you ask.
Practical controls that work today, without asking anyone:
- Clear site data for this domain to remove every key listed above.
- Browse in a private window so nothing persists after you close it.
- Use a content blocker, or your browser's tracking protection, to stop any third-party script from running at all. World Time Lab's tools keep working without them.
- Send Do Not Track or Global Privacy Control signals if you wish. World Time Lab performs no tracking to disable, and does not attempt to detect these signals.
This page describes practice, not legal conclusions. It is a plain account of what this software does, written by the people who built it. It is not legal advice and it does not assert compliance with any particular statute. Anyone operating or reusing this site should have it reviewed against the law that applies to them.
Changes and contact
When this policy changes, the reviewed date at the top of the page changes with it, and the site version tells you which build you are reading. Because the text is generated from the build's own configuration, the third-party section above always describes the build you are actually running rather than a general intention.
Privacy questions about this build. Please say which page you were on and what you want to know.