One Calendar vs Rainlendar

One Calendar

• People who mix Google, Microsoft, iCloud and CalDAV calendars
• Households or workers split between Android, iPhone and Windows
• Buyers who want a one-time payment and no subscription

Rainlendar

• People who want upcoming events and tasks always visible on the desktop
• Households or offices that mix Windows, Mac and Linux computers
• Users who like to restyle an app with skins and scripts
• Buyers who prefer a small one-time payment to a subscription

One Calendar

• A Premium license is needed per platform group: Android, iOS and Windows are each bought separately, because the stores do not allow cross-platform licensing.
• The free version syncs 6 months of past appointments and leaves out search, theming and appointment colors.
• The Microsoft Store page lists the Windows app as free with in-app purchases but does not show the Premium price.
• No web or Linux version is listed. Printing and automatic day rollover are Windows-only Premium features.

Rainlendar

• No mobile or web version. The site suggests syncing both Rainlendar Pro and a phone with Google Calendar instead.
• Sync with Google, Outlook.com, CalDAV and the other online services is limited to Pro, and Outlook support is Windows only.
• The Pro license is sold in euros, at 9.95 EUR; the purchase page shows no US dollar price.
• Rainlendar does not merge calendars from different sources; each stays a separate calendar shown in the same window.

One Calendar

Many calendar services in one app

Connects to Google Calendar, Outlook, Office 365, Exchange, iCloud, Yahoo, GMX, Synology, Nextcloud, ownCloud, Mailbox.org and other CalDAV servers, and shows them together.

Five views with week numbers

Day, week, month, year and list or agenda views, all with week numbers. A quick filter narrows what is shown by calendar color.

Appointments and invitations

Add, change and delete appointments, set up recurrences, invite people to a meeting and accept incoming invitations. Appointments can be shared through apps such as WhatsApp.

Works offline

Appointments can be viewed and managed without an internet connection, according to the vendor's feature list.

Widgets and live tiles

Several widgets are available depending on the operating system, including live tiles on Windows. Choosing which calendars, birthdays and tasks a widget shows is a Premium feature.

Theming and colors

Premium unlocks 170 color options, a background picture, a custom text color and predefined themes, plus a separate color for any single appointment. A dark theme is supported.

Rainlendar

Events and tasks on the desktop

Events and tasks are kept in separate lists that sit on the desktop, and both can also be shown in the calendar window. Several windows can be shown at once, such as the current and the upcoming month.

Alarms with snooze

An alarm can fire ahead of an event or task and be snoozed for later. A single event or task can carry more than one alarm.

Skins and Lua scripting

Skins change how the windows look and can be mixed together, categories change how individual events appear, and Lua scripts can alter how a skin behaves or fetch content from the internet.

Standard iCalendar storage

Events and tasks are saved in the iCalendar format (RFC 2445), by default in a local .ics file, and can be exported or imported as .ics. Settings and events are backed up automatically every day.

Sync with online calendars (Pro)

Pro connects to Google Calendar and Tasks, Office 365 / Outlook.com, CalDAV servers, network shared calendars, Remember The Milk and Toodledo, and to Microsoft Outlook on Windows.

Quick Add and printing

A Quick Add widget creates an event or task from one line of text, including a recurrence pattern and a category. Events and tasks can be printed as a list or a calendar layout, or written to a PDF.

One Calendar

• Free$0

  Day, week, month, year and list views across all connected calendars, with invitations and recurrences and 6 months of past appointments.

• Premium$5.99

  one-time payment per platform group (App Store or Google Play)

  Appointment colors, theming, search, 3 years of history, widget configuration, immediate sync and navigation. Windows needs its own license.

Rainlendar

• Rainlendar Lite€0

  Events, tasks, alarms, skins, printing and iCalendar import and export, with data kept in local files.

• Rainlendar Pro€9.95

  one-time purchase, lifetime license per user

  Adds sync with Google Calendar and Tasks, Office 365 / Outlook.com, CalDAV, Remember The Milk, Toodledo and Outlook on Windows, plus CSV import and export.

One Calendar

No public discounts listed.

Rainlendar

• Lifetime license

  Lifetime Pro license with free upgrades

  The purchase page describes Pro as a single purchase of a lifetime license. The homepage says existing license holders upgrade for free, and the FAQ says one license covers one user on several computers.