Time Zones & World Clocks

Working across time zones — meeting-time finders, world clocks, "stay-awake" utilities. For calendar / scheduling tools see prod-calendar-apps and calendars. For date-handling libraries (developer side) see dates.

Web meeting-time finders

• ★ Every Time Zone — free + paid Pro; the cleanest "drag a slider, see times in 6 cities" tool.
• ★ World Time Buddy (timeanddate.com / worldtimebuddy.com) — free + paid; older but more powerful — great for slack-pasting a converted time table.
• Spacetime (slack app) — free + paid; brings a team timezone bar into Slack.
• There (there.pm) — free + paid; team-roster-with-current-times; popular at distributed startups.
• Doodle — paid + free; meeting-time poll across timezones.

Mac

• ★ Itsycal — free; menubar mini-calendar with optional second-timezone clock.
• MenuBar Stats — paid; multiple timezones in the menu bar.
• CalendarPro — paid; timezone-aware calendar.
• Fantastical — paid; multi-timezone display in event details — see prod-calendar-apps.
• Notion Calendar — free; built-in second-timezone toggle — see prod-calendar-apps.
• macOS World Clock widget (Sonoma+) — free, built-in; widget on desktop / Notification Centre.

Windows

• Windows Clock — free, built-in; can show up to 3 additional clocks (Settings > Time & language > Date & time > Additional clocks).
• T-Clock Redux — free OSS; classic taskbar clock replacement.
• Free Alarm Clock — free; multiple alarms across timezones.

iOS / Android

• Apple Clock app (iOS) — free, built-in; World Clock tab; widgets.
• Google Clock (Android) — free; same idea.
• Klok — paid + free; iOS-only; pretty world-clock app.
• Time Buddy — paid + free; mobile World Time Buddy.

"Stay awake" / no-sleep utilities

• ★ Amphetamine — free, Mac App Store; long-running classic; prevents sleep with rich rules (until time, while on power, while app open).
• ★ Lungo — free + paid; Mac menubar "stay awake" toggle; minimalist.
• caffeinate — free, built-in macOS CLI; caffeinate -d -t 3600 for 1 hour.
• KeepingYouAwake — free OSS Mac; menubar caffeine toggle.
• PowerToys Awake — free; the Win equivalent in PowerToys; toggle "don't sleep."
• Caffeine (Win) — free; older — simulates a key press; lighter than PowerToys.
• Caffeine (Linux GNOME extension) — free OSS.
• Mouse Jiggler apps — free + paid; keep status "available"; controversial.

Cross-timezone calendar tricks

• Set your calendar to show two timezones — Google Calendar / Notion Calendar / Fantastical / Apple Calendar all support this; saves a lookup.
• Set Slack timezone correctly — most chat apps respect it; "8am your time" gets converted.
• Use UTC for log timestamps — see ops logging and tooling like chrony for time sync.
• Decline meetings outside your hours — the meta-fix; tools won't save you from 3am calls.

DST gotchas (worth being aware of)

• DST shifts move differently in US vs EU vs AU vs no-DST regions — every March / November / April / October some recurring meeting drifts by an hour.
• Calendar invites store UTC — if you change timezones (travel) the meeting follows, which can be wrong (you wanted "9am London time" not "9am wherever I am").
• Notion Calendar / Fantastical handle "lock to a timezone" better than the basic apps.

Pricing reality check

• Every Time Zone / World Time Buddy are free for the basic case; paid for embeds / extras.
• Itsycal / Lungo / Amphetamine / KeepingYouAwake / PowerToys Awake / caffeinate are all free.
• Spacetime / There are free for individuals, paid for teams.
• Klok / Time Buddy mobile are cheap.

Patterns that actually work

• ★ One trusted converter, one shortcut to it. Most timezone failures come from approximate math; reach for a tool every time.
• Display two timezones in your calendar — never count on memory.
• Pin your team's working hours in your calendar as all-day blockers — visualises overlap.
• Use Cmd+Space → "5pm Tokyo" in Spotlight / Raycast — built-in for both — fastest one-off conversion.
• Pair "stay awake" with deep-work blocks — turn on Amphetamine when you're focused, off when you're done; lid-close-as-pause is the lazy default that breaks calls.

Pick this if…

• Default web meeting-time finder: Every Time Zone.
• Slack-pasteable converted table: World Time Buddy.
• Slack team time bar: Spacetime.
• Mac menubar calendar + timezone: Itsycal.
• Mac stay-awake free: Amphetamine.
• Mac stay-awake CLI / built-in: caffeinate.
• Windows extra clocks: built-in (Settings > Date & time).
• Windows stay-awake: PowerToys Awake.
• Travel / locked-to-timezone meetings: Notion Calendar or Fantastical — see prod-calendar-apps.