When building Weather & Clock Dashboard — a Firefox new tab extension — one of my core requirements was: no user accounts, no API keys, no data sent to my servers . This post covers how I achieved that using Open-Meteo, a completely free weather API. Why Open-Meteo? Most weather APIs require: Registration + API key management Rate limits tied to an account Potential privacy concerns about who's tracking what Open-Meteo requires none of that. It's: 100% free (10,000 requests/day without an API key) No registration needed Open-source GDPR-compliant by design The Approach The extension uses the browser's built-in Geolocation API to get coordinates, then makes a simple HTTP request to Open-Meteo. Step 1: Get user location navigator . geolocation . getCurrentPosition ( ( position ) => { const { latitude , longitude } = position . coords ; fetchWeather ( latitude , longitude ); }, ( error ) => { console .…