About Central

Central started as a scratch file for scheduling a weekly call across four countries. Counting hours on your fingers stops being funny around the second daylight-saving switch, so the counting moved into a web page.

How it works

Your browser already ships a full IANA time zone database. Central asks it for the offset of each city on the day you picked, lines the 24 hours up side by side, and colours the cells where every location is still inside its working hours.

That means daylight saving is handled for free, and it means there is no server doing the maths. The page is static files; everything happens on your device.

What it does not do

• No accounts, no stored schedules, no invitations.
• No analytics, no cookies, no third-party scripts.
• No calendar integration — copy the hour you picked into whatever calendar you already use.

Sharing

The cities and the date live in the query string, so the address bar is the share button. Send the link and the other side sees exactly the same board.