Comparison

Tuta Calendar vs Flow Interval

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

Head to head
About

Tuta Calendar

This secure calendar app offers end-to-end encryption to protect your events and reminders. It features a user-friendly interface, cross-device syncing, and smart reminders, with a free plan and optional premium upgrades.

Highlights
  • Quantum-safe end-to-end encryption
  • Zero tracking and zero-knowledge architecture
  • Secure event sharing
  • Cross-device syncing
  • Multiple calendar views
  • Smart event reminders
  • Offline access
Read full description

PROTECT YOUR PRIVACY WITH TUTA CALENDAR – FREE, SECURE & ENCRYPTED PLANNER Take control of your schedule with Tuta Calendar, the world’s most secure calendar app, trusted by privacy-conscious users worldwide. With quantum-safe encryption, your events, reminders, and schedules stay private. Fast, open source, and free: Tuta Calendar is built with the highest security standards. Plus, it’s perfectly integrated with the Tuta Mail app. WHY CHOOSE TUTA CALENDAR? Stay Secure • Quantum-Safe Encryption: Your entire schedule, including event details and reminders, is fully end-to-end encrypted – only you can access it. • Zero Tracking: No ads, no profiling, no data sharing. Your calendars are yours. • Zero-Knowledge Architecture: We can’t see your events, meeting times, or attendees. Your schedule is invisible to us. • Secure Event Sharing: Share events securely with Tuta users or external calendars via password-protected invites. • GDPR-Compliant & Hosted in Germany: Protected by strict European privacy laws. Boost Your Productivity • Sync Across Devices: Your events instantly update on mobile, web, and desktop. • Recurring Events: Schedule daily, weekly, monthly, yearly, or custom repeating events. • Multiple Calendar Views: Easily switch between agenda, daily, 3-day, weekly, or monthly views. • External Calendar Sync: Subscribe to external calendars – updates happen automatically. • Unlimited Calendar Management (paid feature): Manage multiple calendars and toggle visibility effortlessly. • Offline Access: View and manage your schedule even without an internet connection. Simple & Intuitive • User-Friendly Interface: Modern, clean design with light and dark modes. • Quick Navigation: Create, edit, or delete events in just a few taps. • Smart Event Reminders: Get encrypted notifications to ensure you never miss an appointment. • Email Integration: Link calendar events directly to your Tuta Mail account for seamless scheduling. PRICING Tuta offers a free plan for everyone, plus premium plans with extra features, available monthly or yearly. Every subscription includes Tuta Mail and Tuta Calendar, seamlessly syncing across all your devices. • Free – Secure, encrypted email and calendar at no cost. • Revolutionary – 20 GB, unlimited calendars, calendar invites and sharing, custom domains, and more. • Legend – 500 GB, unlimited calendars, calendar invites and sharing, 30 email addresses, and advanced features. No matter which plan you choose, your communication remains end-to-end encrypted, private, and completely free from tracking. BONUS: GET TUTA MAIL WITH THE SAME ACCOUNT Your Tuta account gives you access to Tuta Mail, the encrypted email service with the same quantum-safe security as your calendar. One account, two essential privacy tools – completely free. WHO IS BEHIND TUTA? Freedom fighters committed to protecting freedom of speech and your right to privacy! • Developed & Hosted in Germany: Adheres to strict GDPR data protection laws. • Private by Design: We can’t access your data – secure password reset ensures your privacy. • End-to-End Encrypted from the Ground Up: Every event, contact, and reminder is encrypted by default. TRUSTED BY SECURITY EXPERTS "Tuta provides an exceptional level of security and privacy... If security is your priority, there’s not much better than Tuta." — TechRadar "Since Tuta is open source and has amazing products in development, I moved my email there." — Journalist Dan Arel "Tuta’s email security is unmatched. Its mobile apps are fast and user-friendly, with fair pricing and a free option." — CyberSynchs JOIN MILLIONS WHO TRUST TUTA Protect Your Schedule: Download Tuta Calendar today and join millions who trust us for secure, encrypted time management. Website: https://tuta.com Open Source Code: https://github.com/tutao/tutanota Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula

About

Flow Interval

Features
Read full description

Flow Interval – Customizable Step Timer Build your perfect routine with connected timers. Flow Interval lets you create flexible timer sequences for any activity — from high-intensity interval training (HIIT) and yoga flows to Pomodoro study sessions and cooking routines. Key Features: • Flexible Timer Sequences Add unlimited steps and combine “Work,” “Rest,” and “Prep” intervals in any order. • Clear, Intuitive Visuals A circular progress indicator and clean interface show exactly where you are and what’s coming next. • Effortless Editing Duplicate, reorder, and fine-tune steps with ease. Copying “Round 1” instantly creates “Round 2.” • Custom Alerts Choose from multiple sound effects and vibration options to match your style. • Background Support Stay on track with notifications, even when the app is in the background or your screen is locked. • Privacy First No accounts. No tracking. All data stays on your device. Ideal For: • Fitness — HIIT, Tabata, yoga, stretching • Productivity — Pomodoro, presentations, deep work • Lifestyle — meditation, cooking, daily routines Focus on what matters. Let Flow Interval handle the time. Download now and find your flow.

Screenshots

Tuta Calendar4 screens
Flow Interval4 screens

Verdict

The call

The clearest difference is update cadence: Tuta Calendar at weekly against Flow Interval's every 3 months. Tuta Calendar also leads on iOS requirement (16.0 vs 26.0). On price, ads, in-app purchases and device support 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. Tuta Calendar sells 4 in-app purchases, starting at $3.99 per month and Flow Interval sells 3 one-off in-app purchases. Whichever you choose, the download price is not the number that matters.

UpkeepUpdate frequency

Tuta Calendar ships an update weekly, Flow Interval every 3 months. The most recent releases landed on October 27, 2026 and October 7, 2026 respectively.

Scorecard2 real differences · 8 level
Tuta Calendar versus Flow Interval: the parameters behind the verdict, then further details
ParameterTuta CalendarFlow Interval
PriceFreeFree
Rating4.6 (163 ratings) — better—
Positive reviews56.7% of reviews—
Number of ratings163 — better—
Update frequencyWeekly — betterEvery 3 months
AdsNoNo
In-app purchasesYesYes
MonetizationFreemium—
DevicesiPhone, iPadiPhone, iPad
Requires iOS16.0 — better26.0
Further details — not scored
Size45 MB1 MB
Age rating4+4+
DeveloperTutao GmbHTakumi Kanaya

Bugs and requests

Tuta Calendar

Reported bugs

19 issues
  • App crashes frequently
  • Widget is not working or is blank
  • Calendar events not saving or changes not saving
  • App logs out automatically and shows invalid credentials
  • Double reminders for appointments
Show 14 more
  • Lost important information/data
  • Calendar subscriptions duplicate entries
  • Cannot delete calendars or calendar subscriptions
  • Cryptic error messages
  • App constantly crashing on opening
  • Login issues
  • FaceID login not working for free accounts
  • Account creation issues (clock puzzle)
  • Search function doesn't work on app
  • Events from calendar subscriptions not syncing
  • App ignores OS font size settings
  • Issues with recurring events being duplicated
  • Calendar entries not visible without connection
  • Events reload every time the app opens

Requested features

31 requests
  • App for the Watch
  • Icon shows current date
  • Ability to see holidays marked
  • Import from Apple calendar
  • Adjustable app opening view (e.g., month view)
Show 26 more
  • Default appointment length setting
  • Color code appointments on the same calendar
  • Widget that shows more than one day
  • Widget that shows entire month
  • Ability to see monthly and agenda view simultaneously
  • Option to zoom/pinch time intervals
  • Move event blocks by dragging
  • Custom settings for specific days of the week
  • Week numbers displayed
  • Full-featured calendar
  • Option to open locations in other map apps
  • More customizability in UI
  • Better readability for low vision users
  • Adjustable text size respecting OS settings
  • More compact week view
  • Display more event details in month view
  • Quick access to distant calendar days
  • Emojis in events
  • Family planner in free tier
  • On-device notes/non-login option
  • Support for holidays by country/region
  • Dark mode option
  • Advanced analytics dashboard
  • Ability to expand week view to include more than 8 hours
  • Sync with other calendar apps
  • More robust search functionality on mobile app

Flow Interval

Not enough reviews yet to summarise bugs or requests.

In-app purchases

4 purchases

Tuta Calendar

Subscriptions4
  • Revolutionary (Monthly)$3.991 Month
  • Legend (Monthly)$9.991 Month
  • Revolutionary (Yearly)$39.991 Year
Show 1 more
  • Legend (Yearly)$99.991 Year
3 purchases

Flow Interval

One-time3
  • Small Tip$0.99
  • Medium Tip$3.99
  • Large Tip$8.99

Questions

Is Tuta Calendar free?
Tuta Calendar is free to download, with in-app purchases available.
Is Flow Interval free?
Flow Interval is free to download, with in-app purchases available.
Do Tuta Calendar or Flow Interval have ads?
Neither Tuta Calendar nor Flow Interval shows ads.
Which is updated more often, Tuta Calendar or Flow Interval?
Tuta Calendar ships an update weekly, and Flow Interval every 3 months. Most recently, Tuta Calendar was updated on October 27, 2026 and Flow Interval on October 7, 2026.

Other comparisons