Add the cities on your call, drag one slider, and watch every local time update together. Green means working hours, red means the middle of the night there.
Up to 6 zones. Your list is saved on this device.
Fully free. No signup, nothing uploaded. Everything runs in your browser using your device's own time zone data.
It uses your browser's built-in Intl API, the same time zone database your operating system already ships with. No location lookup, no network request, no server involved.
08:00-18:00 local time is marked green, 22:00-07:00 is marked red as likely off hours, and the hour either side of the working window is marked amber as an early or late option. Adjust the slider to see how a proposed time lands in every zone.
Only in your browser's local storage on this device. Nothing is sent anywhere, so it will not show up on another device or browser.