World Clock

WHAT IT DOES

World Clock is a browser extension that displays a floating panel showing the current time in multiple time zones selected by the user. It updates every second in real time, providing a live view of times across the globe. You can add and remove cities and time zones, toggle between 12-hour and 24-hour display formats, and quickly search for cities to add. The panel displays each time zone with its label and current time, including date information for non-local time zones. The tool is ideal for remote workers, international teams, travelers, digital nomads, and anyone who needs to keep track of time across different regions.

WHERE IT RUNS

World Clock runs on any webpage, overlaying a floating panel that does not interfere with page content. It operates entirely in your browser as a lightweight userscript, using JavaScript's Date object to calculate and display times. It works on any page, whether static or dynamic, with no external dependencies. All timezone data and preferences are stored locally using GM_setValue—no data is ever sent to any server.

HOW TO USE

After installation, open the floating panel by clicking the extension icon. The panel displays a list of your selected time zones with their current times, updating every second. Use the 24-hour format toggle to switch between 12-hour (AM/PM) and 24-hour display. To add a timezone, type a city name or timezone in the search input and click Add, or click one of the quick-add buttons (New York, London, Tokyo, Dubai, Sydney). As you type, suggestions from a list of 20+ common timezones will appear. To remove a timezone, click the ✕ button next to it. To reset to the default timezones, click the Reset button. The clock list updates automatically every second—no manual refresh needed. All timezone selections and format preferences are saved globally and persist across browser sessions.

REAL MECHANISM — WHY THIS WORKS

Most world clock tools require internet connectivity to fetch timezone data from external APIs, introducing latency, privacy concerns, and dependency on external services. World Clock uses a different approach: it calculates all times entirely in the browser using JavaScript's built-in Date object and timezone offset arithmetic. For each timezone, the tool stores an offset in hours relative to UTC. When displaying the time, the tool creates a new Date object for the current moment, then adjusts it by adding the offset difference between the user's local timezone and the target timezone. This calculation uses the formula: UTC time + target offset - local offset. The tool updates the display every second using setInterval, ensuring real-time accuracy without any network requests. For timezone identification, the tool uses a curated list of common timezones with their IANA names and approximate offsets, and provides a search interface with autocomplete suggestions. The offset values account for standard time only (DST is not automatically adjusted), but users can approximate DST changes by adjusting offsets manually or using the UTC offset displayed for reference. This approach ensures fast, accurate, and fully private world clock functionality without requiring any external services or network access.

THE PANEL

The floating panel is fully draggable and remembers its position per site, snapping to the edges of the viewport when dragged near them. You can collapse the panel to a small icon to minimize screen distraction and expand it back with a single click. The panel is resizable from the bottom-right corner, giving you more space to view your clocks. Press the Escape key to close the panel instantly. The panel remains open across page navigation within the same domain, maintaining your current view state. All preferences—panel position, selected timezones, and display format—are saved globally for a seamless experience.

PLEASE NOTE

World Clock requires the free BotGentz extension to be installed and enabled, as it relies on the cross-extension messaging API provided by BotGentz for DOM access permissions. Timezone offsets are based on standard time (UTC offset) and do not automatically account for Daylight Saving Time changes. Users may need to adjust offsets manually if DST is in effect and the approximation does not match the actual time. All processing occurs entirely in your browser. No timezone data, location information, or usage data are ever sent to any server. The extension does not read, store, or transmit any personal information. It only calculates and displays times locally at your request.