If you want a world clock in your Firefox browser without opening a separate tab or app, there are a few options. Here's what's actually available and what the differences are.
Why a Browser World Clock?
Mobile apps for world clocks are fine but they require context switching. Web-based clocks (like timeanddate.com) work but require opening and navigating a page. A browser extension that shows world clocks on the new tab sits in between: it's there automatically every time you open a tab, without any intentional navigation.
The value is passive awareness rather than active lookup.
Option 1: New Tab Extension with World Clocks
Weather & Clock Dashboard shows configurable world clocks on the new tab page alongside live weather. You set which cities to show once, and every new tab displays their current time.
Advantages: Combines weather + multiple world clocks in one place. MIT open source, no account required.
Configuration: Install from AMO → click the settings icon → add cities for world clocks → each appears as a labeled clock on the new tab.
Option 2: World Clock Bookmarklet
For a lightweight approach with no extension:
javascript:void(open('https://www.timeanddate.com/worldclock/'))
Bookmark this, add it to your toolbar, and one click opens a world clock tab. No extension required.
Disadvantage: You have to actively click. No passive awareness.
Option 3: Mozilla Firefox's about:newtab with Custom Widget
Firefox doesn't have a native world clock widget on the new tab page. Custom new tab extensions are the only way to add one.
Option 4: Sidebar Extensions
Some Firefox extensions add a persistent sidebar that stays open across tabs. A sidebar clock would be visible all the time — but sidebars take up horizontal screen space, which is usually more precious than vertical.
For a sidebar approach: the Sidebar Web Panel extension (or similar) can load any website in Firefox's sidebar, including world clock sites.
Setting Up Multiple World Clocks in Weather & Clock Dashboard
After installing Weather & Clock Dashboard:
- Open a new tab
- Click the settings/gear icon
- Find the "World Clocks" section
- Add cities: type a city name, select it from the dropdown
- Clocks display immediately
The dashboard shows current weather alongside the clocks, so the new tab becomes a quick-reference panel for both weather and multi-timezone awareness.
Daylight Saving Time Handling
A world clock that handles daylight saving time correctly shows the actual current time (computed from the current offset), not a fixed offset. Weather & Clock Dashboard uses live timezone data, so the clocks automatically show the correct time during DST transitions in different countries — no manual adjustment needed when the US and Europe change on different weeks.
For Remote Teams
If you manage a remote team across time zones, the practical setup:
- Add each team member's city to your world clocks
- After 1-2 weeks of seeing their current time every time you open a tab, you develop intuitive awareness of what time it is for them
- This reduces the "let me check what time it is in Singapore before I send this message" mental overhead
The passive awareness is the feature, not just the clock display.
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