I built Klaxon (https://klaxon.live) as a hobby project — a single static HTML page that fetches the USGS GeoJSON feed client-side and renders it on a Leaflet map. No backend, no database, no tracking, no ads. It deploys as one file on Netlify.

It shows M3.5+ earthquakes (1h/24h/7d), with tectonic plate boundaries overlaid so the spatial pattern is obvious. Popups surface USGS PAGER alert level, MMI, felt reports and tsunami flags when present. For events in Japan it links to JMA, since Japanese users think in shindo intensity rather than magnitude. UI is in English, Japanese and Korean.

Deliberately limited: it does not ingest JMA/NOAA directly (CORS + the static-only constraint), it's not an alerting system, and tsunami support is just a filter on USGS's tsunami flag — not wave modelling. It's a situational-awareness map, not a warning service.

It's a sibling to an earlier project of mine (an outbreak tracker). Happy to answer questions about the architecture or the deliberate constraints.

Wanted to reach the author about the possibility to help translating this to spanish but they made it a bit difficult. The /about page remits you to the /sources page for some reason, and for some other reason the /sources page remits you to hantawatch.net, which seems to be currently down. Oh well.

So you've built a JSON parser

>open dev tools network tab

>backend

There is a frickin backend