I built a Firefox new tab extension — Weather & Clock Dashboard

#javascript #productivity #showdev #sideprojects

I wanted a productive new tab page that loaded instantly. Most weather widgets require API key setup or phone home constantly. So I built my own.

Weather & Clock Dashboard is a Firefox new tab extension. Here's what it does and how it works.

What it does

Live weather — current conditions + 3-day forecast for any city
World clocks — multiple time zones side by side (great for remote teams)
Search bar — uses your default Firefox search engine
Dark/light mode — one-click toggle

Technical approach

Pure HTML/CSS/JS. No React, no Vue, no bundler, no dependencies.

Weather data from Open-Meteo — a free, open-source weather API with no authentication required. The extension geocodes your city on first run, stores coordinates locally, and queries Open-Meteo from the browser directly. Nothing goes through my servers.

Time zones use the browser's built-in Intl.DateTimeFormat API — accurate and no library needed.

Total installed size: ~50KB. Load time: <100ms.

AMO review process

Submitting to Mozilla's Add-on store took about 3 days. The reviewer flagged one issue: I was using innerHTML in one place (fair point), which I fixed before approval. The review process was smooth overall.