One Calendar vs IDRT
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
One Calendar
Consolidate all your digital calendars into a single, easy-to-read view. Manage appointments, events, and birthdays from various providers like Google, Outlook, iCloud, and more, all within one application.
- Integrates multiple calendar providers
- Easy-to-read overview
- Manage appointments and events
- View birthdays
- Cross-platform availability
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The most popular app to view all your calendars like Google, Live, Outlook, iCloud, Exchange, Office365, Yahoo, Nextcloud, Synology, GMX, Mailbox.org, ownCloud and more. OneCalendar integrates all your calendars into an easy-to-read overview. View and manage all your appointments, events and birthdays. OneCalendar is available on all platforms.
IDRT
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IDRT is the club's digital control room; for the board, coaches and volunteers. Bring tasks, meetings, events, volunteers and sponsors together in one place, and give the whole club the full picture in five minutes. Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
Screenshots
Verdict
The clearest difference is update cadence: IDRT at every 3 days against One Calendar's fortnightly. One Calendar's advantage is device support (4 vs 1). On price, ads, in-app purchases and iOS requirement there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. One Calendar sells 1 one-off in-app purchase and IDRT sells 8 in-app purchases, starting at $59.99 per month. Whichever you choose, the download price is not the number that matters.
One Calendar ships an update fortnightly, IDRT every 3 days. The most recent releases landed on October 20, 2026 and October 5, 2026 respectively.
| Parameter | One Calendar | IDRT |
|---|---|---|
| Price | Free | Free |
| Rating | 4.8 (21K ratings) — better | — |
| Positive reviews | 80.7% of reviews | — |
| Number of ratings | 21K — better | — |
| Update frequency | Fortnightly | Every 3 days — better |
| Ads | No | No |
| In-app purchases | Yes | Yes |
| Monetization | Free with in-app purchases | — |
| Devices | iPhone, iPad, iPod, Mac — better | iPhone |
| Requires iOS | 15.0 — better | 16.4 |
| Further details — not scored | ||
| Size | 89 MB | 50 MB |
| Age rating | 12+ | 4+ |
| Developer | Code Spark | Skretteberg AS |
Bugs and requests
One Calendar
Reported bugs
5 issues- Sync errors
- Unresponsive buttons
- Incorrect time zone display
- Duplicate events
- Inability to delete future occurrences of recurring events
Requested features
6 requests- Multiple reminders for events
- Ability to edit recurring events
- Option to change event calendar after creation
- Printing support
- More customization options
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- Widgets for better visibility
IDRT
Not enough reviews yet to summarise bugs or requests.
In-app purchases
One Calendar
- OneCalendar premium$5.99
IDRT
- IDRT Basic$59.991 Month
- IDRT Growth$79.991 Month
- IDRT Basic$179.993 Months
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- IDRT Growth$229.993 Months
- IDRT Basic$299.996 Months
- IDRT Growth$449.996 Months
- IDRT Basic$599.991 Year
- IDRT Growth$799.991 Year
