Comparison

One Calendar vs FreeSlots Share Availability

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

One Calendar

Consolidate all your calendars from various providers into a single, easy-to-read view. Manage appointments, events, and birthdays efficiently across all your devices. Offers a clean interface for seamless organization.

Highlights
  • Integrates multiple calendar providers
  • Unified calendar view
  • Manage appointments and events
  • Syncs across devices
  • Customizable colors and themes
  • Easy to use interface
Features
Read full description

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.

About

FreeSlots Share Availability

Features
Read full description

Someone asks when you're free. FreeSlots checks your calendar and gives you a few good options you can send immediately. No booking links. No account. No calendar upload. REPLY WITH TIMES, NOT LINKS 1. Paste the message: "Do you have 30 minutes Tuesday or Wednesday afternoon?" 2. FreeSlots understands the request and checks all your calendars. 3. You get the best 3 times, spread across days, never on top of a meeting. 4. Tap Copy Reply: "I could do Tuesday at 14:00, Wednesday at 13:30, or Wednesday at 15:00. Would any of those work?" Smart Reply understands durations, days, mornings and afternoons, "after 3", "before lunch" and "except Friday". On iPhones with Apple Intelligence it also reads vague or long messages and email threads, entirely on device. REPLY FROM ANY APP Select a message in Mail, WhatsApp or Slack, tap Share → FreeSlots, and copy your reply without switching apps. Or ask Siri: "Find best times in FreeSlots". IN THEIR LANGUAGE, IN THEIR TIME ZONE Replies match the message: English, German (du or Sie), French or Spanish. If they mention where they are, FreeSlots adds their local times. SHARE YOUR WHOLE WEEK The Availability tab lists every free slot for today, this week or any range. Pick and trim slots, then paste them into Messages, WhatsApp, Mail or Slack. With "Tap to Add", recipients can tap a time to add it to their calendar. YOUR RULES • Working hours: only offer times you actually want to meet. • Buffers around busy events. • Minimum slot length and fixed-length blocks. • Choose which calendars count. COMPLETELY PRIVATE Your calendar never leaves your iPhone. FreeSlots reads when you're busy, not what you're doing. No account, no cloud, no tracking, no ads. Works fully offline. FREE, WITH AN OPTIONAL ONE-TIME PRO Finding free time, the Best 3 quick search (also via Siri: "Find best times in FreeSlots") and Friendly or List replies are free. Smart Reply includes 2 free tries. FreeSlots Pro is a one-time purchase, no subscription: unlimited Smart Reply, Short and Professional reply styles, more than 3 suggestions per request, recipient time zones, and creating replies from a message with Siri & Shortcuts. Bought FreeSlots before it was free? You get Pro automatically.

Screenshots

One Calendar4 screens
FreeSlots Share Availability4 screens

Verdict

The call

The clearest difference is update cadence: FreeSlots Share Availability at weekly against One Calendar's every 3 weeks. One Calendar's advantage is device support (4 vs 1) and iOS requirement (15.0 vs 18.0). On price, ads and in-app purchases 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

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. One Calendar sells 1 one-off in-app purchase and FreeSlots Share Availability sells 1 one-off in-app purchase. Whichever you choose, the download price is not the number that matters.

UpkeepUpdate frequency

One Calendar ships an update every 3 weeks, FreeSlots Share Availability weekly. The most recent releases landed on November 10, 2026 and November 6, 2026 respectively.

Scorecard3 real differences · 7 level
One Calendar versus FreeSlots Share Availability: the parameters behind the verdict, then further details
ParameterOne CalendarFreeSlots Share Availability
PriceFreeFree
Rating4.8 (21K ratings) — better—
Positive reviews80.6% of reviews—
Number of ratings21K — better—
Update frequencyEvery 3 weeksWeekly — better
AdsNoNo
In-app purchasesYesYes
MonetizationFree with in-app purchases—
DevicesiPhone, iPad, iPod, Mac — betteriPhone
Requires iOS15.0 — better18.0
Further details — not scored
Size91 MB3 MB
Age rating12+4+
DeveloperCode SparkChristopher Koch

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
Show 1 more
  • Widgets for better visibility

FreeSlots Share Availability

Not enough reviews yet to summarise bugs or requests.

In-app purchases

1 purchases

One Calendar

One-time1
  • OneCalendar premium$5.99
1 purchases

FreeSlots Share Availability

One-time1
  • FreeSlots Pro$3.99

Questions

Is One Calendar free?
One Calendar is free to download, with in-app purchases available.
Is FreeSlots Share Availability free?
FreeSlots Share Availability is free to download, with in-app purchases available.
Do One Calendar or FreeSlots Share Availability have ads?
Neither One Calendar nor FreeSlots Share Availability shows ads.
Which is updated more often, One Calendar or FreeSlots Share Availability?
One Calendar ships an update every 3 weeks, and FreeSlots Share Availability weekly. Most recently, One Calendar was updated on November 10, 2026 and FreeSlots Share Availability on November 6, 2026.

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