TZ Converter — Timezone Tools by nmsm

TZ Converter turns timezone math into a glance.

Select any time on any web page — an ISO timestamp, a Unix epoch, or a long date like "Wednesday, October 28, 2026, 04:24 UTC" — and a small card shows it in every timezone you care about. No tab-switching, no mental arithmetic.

Features

Select-to-convert: highlight a time, see it in your zones right there.
Pin cards to the page, each with its own colored highlight on the matched text.
Toolbar popup converter: pick a source zone and time, read the rest.
Epoch converter: Unix seconds/milliseconds to readable dates and back.
Custom formats: teach it the date layouts your sites use.
Light / Dark / System theme.
12- or 24-hour clock, your home zone, and your target zones — all configurable.
Private by design Everything runs locally in your browser. The add-on makes no network requests, collects no data, and sends nothing off your device. Its only permission is local storage, used to remember your preferences.

Free and open source: https://github.com/maskeynihal/tz-extension