Frequently Asked Questions

Type a city name into the search field at the top of the app and select from the dropdown. Overlap includes 140+ cities in its built-in list. If your city doesn't appear, it falls back to OpenStreetMap's Nominatim geocoder to find it globally. You can add up to 10 cities at once.

Green means standard working hours (09:00–18:00 local time by default). Amber means early morning (07:00–09:00) or evening (18:00–21:00). Red means outside reasonable working hours. Purple means after midnight to very early morning.

You can customise these hour ranges in the settings panel to match your team's actual working hours — for example, if your team works 08:00–17:00, adjust the green zone to match.

The green zone is the column (or columns) where every city in your grid is simultaneously showing green — meaning everyone is in their standard working hours at the same time. This is your ideal meeting window.

If no column is fully green for all cities, Overlap scores each hour based on how many people are in acceptable hours, and highlights the best available compromise in teal. This is your "least-bad" slot when a perfect overlap doesn't exist.

Up to 10 cities simultaneously. The grid displays all cities as rows with 24 hourly columns. For most distributed teams — even large ones spanning multiple continents — 10 cities is sufficient to represent all timezone clusters in use.

Yes. Your city selection is encoded in the URL automatically. Simply copy the URL from your browser's address bar and share it. Anyone who opens the link will see an exact replica of your grid with the same cities already loaded — no account or signup required.

Click any column in the grid to open the meeting card for that UTC hour. The card displays each city's exact local time for that slot, so you can verify it works for everyone. From the meeting card, click the Google Calendar button to open a pre-filled calendar event with the UTC time and all cities listed in the description. You can also copy a ready-to-paste announcement text with one click.

Yes. Overlap uses the browser's native Intl.DateTimeFormat API for all timezone calculations. This API is updated by your operating system and handles DST transitions automatically based on the current date. The grid always reflects today's actual UTC offsets — you never need to manually adjust for summer or winter time.

This almost always happens during DST transition weeks. The US and Europe change their clocks on different dates in March and October, creating a 1–2 week window where the gap between them changes by one hour. If you scheduled a recurring meeting in one party's local time, the other party will see it shift when clocks change.

The fix: always schedule recurring cross-timezone meetings in UTC. UTC never changes. Your calendar app converts UTC to each attendee's local time automatically and handles DST for you.

India Standard Time (IST) is UTC+5:30 — one of only a handful of timezones worldwide with a 30-minute rather than full-hour offset. This is not a bug. Nepal (UTC+5:45) also uses a non-standard offset. Overlap handles these correctly via the browser's Intl API, so Indian cities will always show times like 14:30 rather than 14:00 or 15:00.

Australia is split. New South Wales (Sydney), Victoria (Melbourne), and ACT observe Daylight Saving Time, switching clocks in October and April. Queensland (Brisbane) does not observe DST and stays at UTC+10 year-round. This means Sydney and Brisbane can differ by one hour during the Australian summer (October–April), even though they're in the same country. Always specify the exact Australian city when scheduling.

Today's offsets, always. The grid recalculates whenever you open it, using the current date. If you open Overlap in December and again in July, cities that observe DST will show different UTC offsets reflecting their actual time on those dates. There is no need to manually change a "summer/winter" toggle.

No. Your city selections are stored only in the URL and your browser's localStorage for convenience. No personal data is transmitted to or stored on any server. Overlap has no backend that processes your city choices. See the Privacy Policy for full details.

Overlap uses no tracking cookies. Your theme preference (light/dark) is saved in localStorage — a browser feature that never leaves your device. Analytics are collected via Google Analytics 4 with IP anonymisation enabled, used only for aggregate traffic data. No third-party advertising or retargeting cookies are set.

Yes, after the initial page load. Overlap makes no external API calls for its core timezone functionality. Everything runs in the browser using the native Intl API and the bundled city database. Once the page has loaded, you can disconnect from the internet and the grid will continue to work correctly.

Yes. If your city isn't in the built-in list of 140+ cities, Overlap automatically falls back to OpenStreetMap's Nominatim geocoder. Type your city name and if it can be geocoded, it will be added to the grid with the correct timezone. If the geocoder can't find your city, contact us and we'll consider adding it to the built-in list.

City names work best because they map directly to IANA timezone identifiers (like America/New_York or Europe/London). Regions and states can be ambiguous — a state may span multiple timezones. If you're in a large country with multiple timezones, search for the nearest major city in your timezone rather than the country or state name.