Report updated May 20, 2026
Once(A special period tracker)
For women seeking to track menstrual cycles, manage fertility, and record health symptoms in a private, organized digital planner.
Once(A special period tracker) is an established health & fitness app that is free with in-app purchases. With a 4.4/5 rating from 359.4K reviews, it shows polarized user reception. Users particularly appreciate long-term reliability of cycle tracking keeps users engaged for over a decade, though widget functionality fails to update or count down days accurately post-update remains a common concern.
What is Once(A special period tracker)?
Once is a period and fertility tracker for women, providing cycle prediction, symptom logging, and lifestyle tips on iOS and Android.
Users hire Once to manage irregular cycles and fertility windows through a simple, private digital planner that avoids the complexity of broader health platforms.
Current Momentum
v1.9 · 6d ago
Maintenance- Ships general bug fixes.
- Last major update May 2026.
Active Nemesis
Clue Period & Cycle Tracker
By BioWink
Other Rivals
7-Day Rank Pulse 🇺🇸
Health & FitnessNo ranking data
Rating Pulse 🇺🇸
Recent User MoodAI-powered deep analysis surfacing high-signal insights. Still in beta, accuracy improves daily. For informational purposes only.
What makes this app unique?
What Does It Look Like?
How Is The App's Momentum Right Now?
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What Are The Key Features?
Calculates irregular cycles based on historical input.
Calculates fertility windows based on biological survival rates.
Provides cycle-specific lifestyle and health advice.
How much does it cost?
- Free with ads
- In-app purchases
Freemium model utilizes ad-supported access to drive mass adoption, with IAP gates for specific content or utility.
Who Built It?
Malang Studio Co. Ltd,
Gamifying daily routines and providing localized utility tools to help users manage morning habits, transit, and personal health.
Portfolio
4
Apps
Who is Malang Studio Co. Ltd,?
Malang Studio differentiates itself by applying gamification and character-driven mechanics to high-friction daily utilities, such as morning alarms. Their portfolio is strategically anchored in the South Korean market, utilizing localized transit data and proximity-based social features to maintain a defensible niche against global utility incumbents. The publisher demonstrates a high-velocity maintenance strategy, frequently updating legacy titles to preserve functionality and user retention.
Who is Malang Studio Co. Ltd, for?
- General mobile users in South Korea
- Global audiences seeking gamified tools for routine management
- Health tracking
Portfolio momentum
Maintains a high update frequency with 9 releases across 4 apps in the last 6 months, indicating active optimization of their core portfolio.
What other apps does Malang Studio Co. Ltd, make?
What do users think recently?
Low confidence · Latest 61 of 91 total reviews analyzed · Based on 91 reviews. Signal may be noisy.
How did the latest release land?
What is the recent mood?
Recent user voice shows a mixed sentiment. Users appreciate long-term reliability of cycle tracking keeps users engaged for over a decade, but report widget functionality fails to update or count down days accurately post-update.
What Users Love
What Frustrates Users
What Users Want
What is the competitive landscape for Once(A special period tracker)?
How's The Health & Fitness Market?
How does it evolve in the Health & Fitness market?
Once maintains a significant Android footprint with over 359,000 ratings, but its iOS presence is limited to 84 ratings. The disparity suggests the app is currently failing to convert or retain the higher-value iOS demographic relative to its Android legacy.
| Country | Category | Chart | Rank | Change |
|---|---|---|---|---|
| 🇸🇪 Sweden | Health & Fitness | AndroidFree | #178 | NEW |
The rivals identified
The Nemesis
Head to Head
The target app must pivot toward a more data-informed, clinical value proposition to compete with Clue's authority-based moat.
What sets Once(A special period tracker) apart
Provides a more streamlined, minimalist interface for users who find complex health-tracking dashboards overwhelming
What's Clue Period & Cycle Tracker's Edge
Leverages a massive, active community to provide data-driven cycle predictions that outperform basic calendar-based logic
Maintains a rigorous, science-first brand positioning that builds deeper long-term trust with health-conscious users
Contenders
Focuses on a comprehensive, all-in-one dashboard that includes weight, mood, and symptom tracking in one view
Maintains a legacy-style interface that appeals to users who prefer static, calendar-first navigation over modern feeds
Aggressive update schedule with 23 releases in six months indicates rapid feature iteration and bug fixing
Optimized for high-frequency user interaction through persistent notification-driven engagement loops
Stardust Period Tracker
★4.8 (101.7K)Stardust App LLC (New York)
⚡Captures a younger demographic by blending cycle tracking with astrological and lifestyle-oriented content.
Integrates astrological insights to create a unique, lifestyle-focused user experience that transcends basic health tracking
Targets a specific, younger audience segment that values social-media-style aesthetics and community-driven content
Period Tracker Period Calendar
★4.9 (167.5K)ABISHKKING LIMITED.
⚡Maintains a massive, loyal user base through a simple, reliable, and highly-rated utility-first approach.
Prioritizes extreme ease-of-use for quick daily logging, minimizing the time required to record cycle data
Maintains a high-rating consistency by focusing on core utility rather than feature bloat or social integration
Peers
Offers a holistic health ecosystem that connects cycle data to broader wellness metrics like sleep and nutrition
Provides a community-driven forum feature that allows users to discuss health concerns with peers
Native OS integration allows for seamless data syncing with Apple Watch and other health-tracking hardware
Eliminates the need for third-party apps by providing a centralized, secure repository for all health data
Cycles: Period & Cycle Tracker
★4.7 (25.4K)Perigee
A design-focused peer that emphasizes simplicity and privacy for the user.
Employs a highly minimalist, gesture-based interface that removes visual clutter for a focused user experience
Positions itself as a privacy-first alternative by minimizing data collection and external cloud dependencies
New Kids on the Block
Moody Month: Hormone Tracker
★4.6 (879)We Are Moody Ltd
⚡An emerging threat focusing on the intersection of hormonal health and emotional well-being.
Maps hormonal fluctuations directly to emotional and mood patterns to provide actionable lifestyle advice
Uses a content-led approach to educate users on how cycle phases impact daily mental health
The outtake for Once(A special period tracker)
Strengths to defend, gaps to attack
Core Strengths
- 15-year historical data depth creates high switching costs
- Minimalist design reduces cognitive load for daily logging
- Privacy-focused lock function builds trust for sensitive data
Critical Frictions
- Data backup failures prevent device migration
- Widget update latency disrupts primary daily utility
- Calculation errors in recent builds erode trust
Growth Levers
- Integration of clinical-grade insights
- Modernization of cloud-sync infrastructure
Market Threats
- Clue’s clinical research partnerships outpace calendar-based logic
- Platform-level incumbents like Apple Health reduce third-party utility
What are the next best moves?
Rebuild cloud-sync infrastructure because backup failures are the top churn driver for long-term users → stabilize retention
Data synchronization and backup failures are cited as primary reasons for historical record loss.
Trade-off: Pause the development of new lifestyle tips — data persistence is a higher-impact retention lever.
Audit widget update logic because widget failure is the #1 daily utility complaint → restore daily habit
Users report the home screen widget does not reflect current cycle data post-update.
Trade-off: Same-quarter capacity available — no major lever displaced.
A counter-intuitive read
The app's decade-long history is a liability, not an asset, because the legacy architecture prevents the data-persistence and cloud-sync standards that modern users now treat as baseline requirements.
Feature Gaps vs Competitors
- Clinical-grade cycle insights (available in Clue)
- Holistic health ecosystem integration (available in Glow Eve)
Key Takeaways
- Prioritize data-persistence infrastructure to stop the churn of decade-long users.
- Pivot from simple calendar-based logic toward data-informed, clinical value propositions.
- Address widget and sync regressions immediately to defend the core daily habit loop.
Once retains a loyal base through simplicity, but technical regressions in sync and widget reliability are driving churn, so the PM must prioritize infrastructure stability over new content to prevent further erosion of the decade-long user base.
Where Is It Heading?
Declining
The period-tracker market is consolidating around science-first platforms that offer clinical research partnerships and seamless cross-device syncing. Once is currently exposed: its reliance on legacy calendar logic leaves it vulnerable to rivals that provide more actionable health data, so the app must modernize its infrastructure to remain relevant.
Data backup failures prevent device migration, which drives churn among the most tenured, high-value users.
Widget update latency disrupts the daily habit loop, which compounds the negative sentiment already visible in recent reviews.