Timezone Calendar is a free iPhone application developed by Geospike Pty Ltd. It falls under the category of Utilities & Tools and provides a dynamic slide ruler for cross-timezone planning. With Timezone Calendar, scheduling something across multiple timezones becomes a breeze.

One of the standout features of Timezone Calendar is its ability to compare multiple timezones side-by-side. This makes it easy to select a time that works for everyone involved. The app integrates with the iOS Calendar, allowing you to display your existing events and create new ones that are synced with your system calendar.

Timezone Calendar also offers a handy Today widget, which allows you to view your favorite timezones without even unlocking your phone. The app supports an unlimited number of timezones, so you can compare as many as you need.

With Timezone Calendar, you can easily navigate through different dates and plan events in the future. The app displays the date and day of the week along with the time, making it easy to stay organized. It also supports daylight saving time and even nautical time zones.

In addition, Timezone Calendar allows you to search for timezones by city name, timezone abbreviation, or UTC offset, making it simple to add new timezones to your list. You can also rename your timezones and give them nicknames for easy identification.

Overall, Timezone Calendar is a powerful tool for anyone who needs to schedule across multiple timezones. Its user-friendly interface, extensive feature list, and seamless integration with the iOS Calendar make it a must-have app for frequent travelers, international teams, and anyone dealing with global time differences.