Zoho Calendar!

Microsoft Outlook, part of the Microsoft Office Suite (not to be confused with Microsoft Outlook Express), is a personal information manager that lets you manage your e-mail, calendar, contacts, and tasks.

eM Client is a full featured email client with a modern and easy to use interface. - offers calendar, tasks, contacts and even chat.- fully optimized to run smoothly on Windows XP, Vista, 7, 8 and 10.- supports all major services including Gmail, Exchange, iCloud, and Outlook.com.- easily imports your data from most of the other e-mail clients. This includes Microsoft Outlook, Outlook Express, Windows Mail, Windows Live Mail, Thunderbird, The Bat and more.- fully supports touch devices like touch-enabled laptops, tablets and hybrid devices. Use your email client easily in a modern way.- finds any email, contact or attachment in seconds with eM Client's super-fast search. »

Keep track of your busy schedule and share it with others using Calendar. Create separate calendars — one for home, another for school, a third for work, and so on. See all your calendars in a single window or choose to see only the calendars you want. Calendar lets you create invitations using information from Contacts, update your guest list, keep track of responses, and receive the latest status information. When you or another Mac user receives a Calendar invitation via Mail, it’s automatically added. Calendar also works with iCloud, Yahoo!, and Google. And when you use iCloud, every Calendar edit you make on your Mac automatically appears on your iPad, iPhone, and iPod touch. So no dinner dates are missed, no meeting goes unattended, and no anniversary is forgotten. »

Rainlendar is a feature rich calendar application that is easy to use and doesn't take much space on your desktop. The application is platform independent so you can run it on all major operating systems: Windows, Linux and Mac OS X. The appearance can be customized with skins and you can even mix different skins together. It is possible to use Rainlendar with other calendar applications too. Rainlendar uses the standard iCalendar format to store its events and tasks so you can easily transfer them between applications. You can also subscribe to online calendars including the Google Calendar and edit your Outlook appointments directly in Rainlendar*. »

Kolab is entirely Free and Open Source Software (a.k.a. FOSS), and uses Open Standards. We’ll get to why this is important to us, and hope that it is important to you thereafter.

An offline calendar without any other calendar integration. You can easily create recurring events and setup reminders, it can also display week numbers.

CalenGoo gives you a fast and easy way to access and change your Google Calendar (or Google Apps Calendar) with your Android device. It can either work with the built-in calendar or it can sync directly with Google.

30 Boxes is an online calendering tool.

Make a beautiful embeddable booking widget in minutes. Free to use with Google Calendar support. Use it for customer support, client calls or meeting appointments. Built by Timekit.io.

BEAUTIFULLY DESIGNEDDigiCal’s diary planner and organizer provides a clear and beautiful overview for your events and appointments.• Conveniently switch between 7 calendar views (day, week, week agenda, month calendar, text month, year and list view in portrait and landscape mode).• The slick dark theme allows for better visibility in low-light settings and night mode.• Event keyword image matching available in all 27 languages!• 6 highly customizable widgets with different theme styles and views: (FREE: list, day, day list, day grid widgets; PREMIUM: 2 extra widgets –text month and month calendar widget)• Intuitive navigation between days, weeks and months with zoomable day and week view. »

The fast calendar for iPhone. Add an event in just two quick taps. See how full your week or day is at a glance. It works with the built-in iPhone calendar but it’s faster.

MemoCalendar.net is a light-weight and easy-to-use online calendar like a usual memo calendar on the wall. Behind every day a small note can be deposited. MemoCalendar.net is free and without registration (login) usable.