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The One Calendar Insider’s Guide

Everything we know about One Calendar in one document: what it costs, its grades, getting a refund, getting help and what else to look at. Read it here, or keep a copy.

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ToolGPAOctober 2026

One Calendar

The Insider’s Guide

One view of all your calendars on Android, Apple and Windows

Every plan, grade, refund rule and rival among calendar and scheduling apps, read from One Calendar’s own pages.

Made by Code Spark · checked Oct 9, 2026 · toolgpa.com

3.2GPA

Contents

  1. 01WelcomeWhat it is, who it suits, its grades and the ten things to know first
  2. 02What it costsEvery plan, the free plan, ways to pay less and how prices have moved
  3. 03What it doesIts main features, where it runs, what it works with and who makes it
  4. 04Where it standsIts grades against its category, and whether to keep it or make your own
  5. 05The alternativesThe tools it is most often weighed against, side by side
  6. 06Quick answersThe questions people ask about it, each answered in a line or two
  7. 07About ToolGPAWho made this guide, what else is on the site, and how to cite it

ToolGPA put this guide together from One Calendar’s own pages, its app-store listings and our grades. Every fact in it is on One Calendar’s page too, where it is kept up to date. Checked Oct 9, 2026.

Part 01 · Overview

Welcome

What it is, who it suits, its grades and the ten things to know first

3.2

GPA, above 66 of the 74 other calendar and scheduling apps we grade

One Calendar, written OneCalendar on its own site, is a calendar app from the Dutch company Code Spark for Android, iPhone, iPad, Mac and Windows. It connects directly to accounts such as Google, Outlook, Office 365, Exchange, iCloud, Yahoo, Nextcloud and other CalDAV servers and shows them in one overview with day, week, month, year and list views. The app is free, and a one-time Premium license adds search, theming, appointment colors and a longer history.

To get you started, here are 9 things to know about One Calendar, taken from its own pages and our grades.

Connect your accounts and they show up together, with a quick filter to narrow by calendar color.
From our grade for ease of use
  1. 1

    Best for all your calendar accounts in one plain view

    You pay per platform, so Android, iOS and Windows each need their own license, and the Windows price isn't shown.

  2. 2

    What it costs

    Paid plans start at $5.99 one-time per platform (App Store or Google Play).

  3. 3

    There is a free plan

    Free version with all five views, appointment management and every supported calendar type, syncing 6 months of past appointments. Search, theming, appointment colors and widget configuration need Premium.

  4. 4

    It runs on 4 platforms

    Android, iOS, macOS and Windows.

  5. 5

    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.

  6. 6

    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.

  7. 7

    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.

  8. 8

    A 3.2 GPA, above 66 of 74

    That is against the other calendar and scheduling apps we grade, on value, the free plan, features, ease of use and platforms.

  9. 9

    Keep it

    The plain part of One Calendar you could make: calendar. What surrounds it you could not. The 4 things listed below take a company, not a weekend.

One Calendar at a glance

Pricing
Free plan, from $5.99 one-time per platform (App Store or Google Play)
Free plan
Yes
Free trial
None stated
Runs on
macOS, Windows, iOS, Android
Made by
Code Spark
Category
Calendar & Scheduling
Our grade
3.2 GPA, very good
Store rating
4.8 on the App Store, 20,678 ratings

The report card

Best for all your calendar accounts in one plain view

One Calendar pulls Google, Outlook, iCloud, Exchange and CalDAV calendars into one overview on Android, iPhone, Mac and Windows, free, with Premium at $5.99 once. You pay per platform, so Android, iOS and Windows each need their own license, and the Windows price isn't shown. Free keeps 6 months of history and leaves out search and colors, and there are no tasks and no web version.

ToolGPA report cardOne CalendarGraded Oct 10, 2026
SubjectGradeComment
Value for moneyAPremium is $5.99 paid once, where this category's middle plan wants $6 every month. You do buy it per platform group, so Android, iOS and Windows are separate licenses, and the Microsoft Store page doesn't show its price.
Free plan and trialBThe free version carries all five views, every supported calendar type, invitations and recurrences. The ceilings: 6 months of past appointments, and no search, theming or appointment colors.
FeaturesCA plain calendar that does the basics across a lot of accounts: Google, Outlook, Office 365, Exchange, iCloud, Yahoo, Nextcloud and other CalDAV servers, five views, offline use. The gaps are clear enough. No tasks, no plain-language entry, search is Premium and printing is a Windows-only extra.
Ease of useA4.8 from about 21,000 App Store ratings. Connect your accounts and they show up together, with a quick filter to narrow by calendar color.
Platforms and integrationsBAndroid, iPhone, iPad, Mac and Windows, connecting to a long list of services including any CalDAV server. There's no web version, no Linux and no API.
Grade point averageVery good, out of 4.03.2

An A is worth 4 points, a B 3, a C 2, a D 1 and an F nothing. The GPA is the average of the five.

Who One Calendar is for

  • Fits if your calendars are split across Google, Microsoft, iCloud and a CalDAV server
  • Works for households on a mix of Android, iPhone and Windows, each device family buying its own license

Who it is not for

  • Not for you if you expect one purchase to cover every device, since Android, iOS and Windows are licensed separately
  • Tight if you're staying free and need to look things up, because search is Premium and history stops at 6 months
  • Skip it if you want your calendar in a browser or on Linux, as neither version is listed
  • Watch out: the Microsoft Store doesn't show the Windows Premium price, and printing is a Windows-only extra
  • Too light for anyone wanting tasks or typed natural-language entry, which aren't listed

Good to know

Good for

  • 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

Worth knowing

  • 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.

Part 02 · Pricing

What it costs

Every plan, the free plan, ways to pay less and how prices have moved

$5.99 one-time

To start. There is a free plan too

One Calendar has a free plan. Paid plans start at $5.99 one-time per platform (App Store or Google Play).

You do buy it per platform group, so Android, iOS and Windows are separate licenses, and the Microsoft Store page doesn't show its price.
From our grade for value for money

  • 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.

The free plan

Free version with all five views, appointment management and every supported calendar type, syncing 6 months of past appointments. Search, theming, appointment colors and widget configuration need Premium.

Read from apps.apple.com on Oct 9, 2026.

What the app costs elsewhere

Each country’s App Store price for “OneCalendar premium”, against $5.99 in the United States, in dollars at the day’s rate. The four cheapest and the four dearest of 11.

CountryPrice thereIn dollarsAgainst the US
Canada$7.99$5.626% less
Turkey₺299,99$6.10about the same
India₹ 599$6.19about the same
Philippines₱ 399.00$6.356% more
South AfricaR119.99$7.2621% more
Germany6,99 €$7.8331% more
United Kingdom£5.99$7.9232% more
BrazilR$ 39,90$7.9733% more

Part 03 · Features

What it does

Its main features, where it runs, what it works with and who makes it

4

Places it runs: macOS, Windows, iOS and Android

One view of all your calendars on Android, Apple and Windows. Here is what it does, as its own site describes it, and what it covers: works offline, one-time purchase, calendar.

No tasks, no plain-language entry, search is Premium and printing is a Windows-only extra.
From our grade for features
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.

Where it runs

  • macOS
  • Windows
  • iOS
  • Android

What it works with

  • Google Calendar
  • Outlook
  • Office 365
  • Exchange
  • iCloud
  • Yahoo Calendar
  • Nextcloud
  • Synology

One Calendar is made by Code Spark.

Part 04 · Standing

Where it stands

Its grades against its category, and whether to keep it or make your own

66/74

Other calendar and scheduling apps it is graded above

One Calendar's GPA of 3.2 is higher than 66 of the 74 other calendar and scheduling apps we grade, and level with 5.

It stands best on ease of use (A, above 62 of 74) and worst on features (C, above 3).

Each grade against the category

Every bar is all 75 calendar and scheduling apps we grade, cut by the letter each got. One Calendar’s own letter is outlined.

  • AValue for moneyAbove 45 of 74
  • BFree plan and trialAbove 41 of 74
  • CFeaturesAbove 3 of 74
  • AEase of useAbove 62 of 74
  • BPlatforms and integrationsAbove 25 of 74

Keep it, or make your own?

Whether this is something you could build for yourself with an AI app builder, and what you would give up.

Keep it

The plain part of One Calendar you could make: calendar. What surrounds it you could not. The 4 things listed below take a company, not a weekend.

It is one of the better ones too: its GPA of 3.2 is higher than 66 of the 74 other calendar and scheduling apps we grade. It costs $5.99, paid once.

What you could make

  • Calendar: an app builder makes this well.

What you could not

  • Apps for macOS, Windows, iOS and Android that stay in step with each other.
  • It plugs into other products, Google Calendar, Outlook and Office 365 among them.
  • Hooks into the device itself: widgets.
  • Sharing with other people, which means accounts and invitations.

What this rests on. One Calendar’s listing: what it does, where it runs, what it plugs into and what it costs. It is a judgement about the kind of software this is. We have not built a replacement for it, and making your own means looking after it too. How we decide, and every tool’s verdict.

Part 05 · Alternatives

The alternatives

The tools it is most often weighed against, side by side

DigiCal, Business Calendar 2, CalenGoo, aCalendar and Google Calendar

The 5 tools One Calendar is most often weighed against, with where each one differs from it.

  • 2.6GPA

    DigiCal

    Free plan · from $5.49 one-time

    Android calendar with seven views, widgets and weather forecasts.

    • Only One Calendar lists iOS, macOS and Windows apps.
    One Calendar and DigiCal compared in full
  • 2.2GPA

    Business Calendar 2

    Free plan · from $1.49

    Android calendar and task app with widgets and a Pro upgrade.

    • Only One Calendar lists iOS, macOS and Windows apps.
    • One Calendar can be bought with a one-time purchase.
    • Business Calendar 2 also covers templates and tasks.
    One Calendar and Business Calendar 2 compared in full
  • 2.8GPA

    CalenGoo

    Free trial · from $5.99 one-time

    Highly configurable calendar and task app sold as a one-time purchase.

    • One Calendar has a free plan. CalenGoo does not, though it has a free trial.
    • Only CalenGoo lists a Linux app.
    • CalenGoo also covers templates, tasks and natural-language input.
    One Calendar and CalenGoo compared in full
  • 2.6GPA

    aCalendar

    Free plan · from $2.49 one-time

    Android calendar with widgets, tasks and one-time upgrades.

    • Only One Calendar lists iOS, macOS and Windows apps.
    • aCalendar also covers tasks.
    One Calendar and aCalendar compared in full
  • 3.4GPA

    Google Calendar

    Free plan · from $7/mo

    Online calendar from Google, free with a personal account.

    • Only One Calendar lists macOS and Windows apps.
    • Only Google Calendar lists a web app.
    • One Calendar can be bought with a one-time purchase.
    One Calendar and Google Calendar compared in full

Part 06 · Questions

Quick answers

The questions people ask about it, each answered in a line or two

12

Questions, each answered in a line or two

The short version of everything above, for when you only need the answer. Each one is told in full in its part of the guide.

Is One Calendar free?

One Calendar has a free plan. Free version with all five views, appointment management and every supported calendar type, syncing 6 months of past appointments.

How much does One Calendar cost?

One Calendar lists 2 plans. Free: $0.

What platforms does One Calendar work on?

One Calendar is available on Android, iOS, macOS and Windows.

How is One Calendar rated?

One Calendar's iPhone and iPad app averages 4.8 out of 5 from 20,678 ratings on the App Store in the United States, as read on Oct 9, 2026.

Does One Calendar have a Linux app?

No Linux app was listed when its pages were read on Oct 9, 2026. One Calendar is listed for Android, iOS, macOS and Windows.

Is One Calendar open source?

One Calendar is not described as open source on its own site, as read on Oct 9, 2026.

Does One Calendar work offline?

Yes, according to its own site. What works without a connection differs by plan and platform, so check the vendor's page for the detail.

What does One Calendar integrate with?

One Calendar's listing names Google Calendar, Outlook, Office 365, Exchange, iCloud, Yahoo Calendar, Nextcloud and Synology.

Who makes One Calendar?

One Calendar is made by Code Spark.

What are the alternatives to One Calendar?

The closest alternatives to One Calendar in our directory are DigiCal, Business Calendar 2, CalenGoo, aCalendar and Google Calendar.

How does One Calendar compare with other calendar and scheduling apps?

One Calendar's GPA of 3.2 is higher than 66 of the 74 other calendar and scheduling apps we grade, and level with 5.

Could I make my own version of One Calendar?

The plain part of One Calendar you could make: calendar. What surrounds it you could not.

Where this guide comes from

The prices, plans, platforms and features were read from One Calendar’s own pages on Oct 9, 2026, and the grades were given on Oct 10, 2026. Graded from this listing, whose facts were read from OneCalendar's own pages on 9 October 2026, and its App Store rating. Also tested with a demo account on 2026-04-17.

Every tool we list gets five grades, A to F, each with its reason, and a GPA that averages them. How each is decided is at toolgpa.com/grades. This guide is ToolGPA’s own work; it is not made, paid for or approved by Code Spark. Prices change, so check onecalendar.nl before you buy.

Part 07 · About

About ToolGPA

Who made this guide, what else is on the site, and how to cite it

3,189

Tools graded, in 94 categories

ToolGPA grades software the way a school report grades a pupil: five subjects, a letter for each with the reason written beside it, and a GPA that averages them. Prices, plans and platforms are read from each maker’s own pages and dated, so you always know how fresh a figure is.

Every grade, review and ranking on ToolGPA is our own judgement. No company can pay for a grade or change one. Every tool on the site has a guide like this one, free to download and pass on. It all lives at toolgpa.com.

  • 3,189

    tools graded

  • 94

    categories

  • 426

    price changes on record

  • 579

    apps priced in 12 countries

What else is on toolgpa.com

Scan for the live page

Prices and grades as they are today

Quoting this guide?

Please name ToolGPA and link to the live page, so readers can check the figures for themselves:

ToolGPA, "One Calendar: The Insider's Guide", checked Oct 9, 2026. https://toolgpa.com/tools/one-calendar

Know someone choosing between calendar and scheduling apps?

Send them this guide: toolgpa.com/tools/one-calendar/guide

ToolGPA elsewhere: youtube.com/@toolgpa

See our other guides

The best-graded calendar and scheduling apps after One Calendar, each with an Insider's Guide of its own.

ToolGPA

Choosing software? Every tool graded, every price dated.

Compare tools at toolgpa.com ›

Everything in this guide is ToolGPA’s own summary of what One Calendar’s pages, its app-store listings and public reviews said on the dates shown. Grades are our judgement under the rules at toolgpa.com/grades. Every grade, review and ranking on ToolGPA is our own judgement. No company can pay for a grade or change one. One Calendar is a trademark of its owner, and this guide is not made, paid for or approved by Code Spark. Prices and plans change: check onecalendar.nl before you buy.