# Once(A special period tracker)

> Period, ovulation, and fertile window tracker with pregnancy risk estimation. (iPhone/iPad app by Malang Studio Co. Ltd,.)

- Source: https://appshunter.io/ios/app/oncea-special-period-tracker/id990572129 (this page in markdown: same URL + `.md`)
- Developer: [Malang Studio Co. Ltd,](https://appshunter.io/developer/523490027)
- Category: Health & Fitness, Lifestyle
- Price: Free with in-app purchases
- Rating: 3.70/5 from 86 App Store ratings · 91 written reviews indexed
- Age rating: 12+
- Requires: iOS 15.6 · 80 MB
- Languages: American English, Japanese, Korean, Chinese (Simplified, China), Thai, Chinese (Traditional, Taiwan)
- Released: 2015-06-17
- Data updated: 2026-09-09
- Monetization: free with in-app purchases
- User reviews in markdown: https://appshunter.io/ios/app/oncea-special-period-tracker/id990572129/reviews.md

## What is Once(A special period tracker)?

To all the women who need a calendar to write down upcoming period 
To all the women who need a journal to manage irregular period cycle and cramp
To all the women who want to know ovulation, fertile, birth control, and possibility of pregnancy all in one calendar
To all the women who were bothered to mark their period on the calendar
To all the women who secretly recorded symptoms on their planner
Must-have! Period tracker, Once!
[Kept both simplicity and functionality of period tracker!]

** Estimated period calendar which gets more accurate as you use it!
Once automatically calculates your irregular period cycle and cramp smartly!
In the period calendar, you can view your estimated period, fertile which has high percentage of pregnancy, and ovulation, all in one-step! In the calendar history list, you can view all your past period cycle in one-step.

** Take care of your fertile and ovulation meticulously!
You can take care of yourself even better with the calendar which shows fertile, ovulation, and estimated period in a glimpse of eye!

** A widget which allows you to check precious data quickly!
The first period calendar ever! Check the important info (estimated period, ovulation, and percentage of pregnancy) more quickly and easily with our widget.

** Percentage of pregnancy calculated scientifically!
Based on egg’s duration of life, 24hrs, and sperms’ duration of life, 3~5 days, we indicate percentage of pregnancy “high” for one day before and after the ovulation, and “moderate” for fertile.

** The day you must be prepared! Prepare it in advance!
To make you not embarrassed on the day! We notify the important dates (estimated period, ovulation/fertile and whenever you want) you in advance with witty message and alarm. We provide the alarm function of contraception pills. 

** Keep your precious daily data conveniently!
Keep your data easier than a journal. All your recorded period, intimate days, memo, and automatically calculated ovulation and fertile… and all other data… You only need to sign-up to keep them all! 

** Not just your period, but your secret intimate days!
You can record your status and symptoms such as the first day of period and period cramps, whenever you want.
Once, which you can record all your secrets such as intimate days! Don’t worry about others having a look at your diary, with our lock function.

** Simple and stylish design capturing women’s mind!
“The better it looks, the more convenient to use.” We have enhanced usability of calendar, by simple and stylish design. In the period calendar, you can view your estimated period, and ovulation, all in one-step. Just like a pretty planner you want to show off, the calendar design won’t be embarrass you even when you install it!


[We have added special features only available in Once!]

** Charming and interesting “Today’s Tip”, which changes depending on your cycle!
Beauty tips which makes you attractive and charming depending on period cycle, ovulation, and fertile. Useful real-life know-hows, useful diet tips, tips to prevent pregnancy, tips for healthy relationships… we enhance your charm by providing various tips!

** Once events made exclusively for women! 
Staring from Once beauty pouch fully packed with sense, and Once doctor which provides exact information on diet and health… We hold various events on beauty, diet, and health, which suits women’s appetite! 

---------------------------------------

Please be with Once, we are doing our best to bring you the best service :D
Developer: Malang Studio (http://malangstudio.com/)

* You can get faster response for questions regarding Once if you write to once@malang.kr!


This service includes In-app Purchase items, and a separate fee will be charged for purchase.

- Terms of Service : https://bit.ly/38zBlvj
- Privacy Policy : https://bit.ly/3iqaZ3g

Contact
Tel. support@malang.kr / +827050386396
Address. 11th floor, 508, Eonju-ro, Gangnam-gu, Seoul, Republic of Korea

## Key features

- Period cycle tracking
- Ovulation and fertile window prediction
- Pregnancy risk calculation
- Symptom logging
- Customizable reminders
- Home screen widget
- Cycle-based tips

## Pricing and in-app purchases

Base price: Free.

**One-time purchases**

| Purchase | Price | Type |
| --- | --- | --- |
| Ad-Free Ticket (30days) | $0.99 | one-time |


## Recent user reviews (10 of 91)

All indexed reviews: https://appshunter.io/ios/app/oncea-special-period-tracker/id990572129/reviews.md

### 3/5 — Too many ads

*2026-08-28*

Too many Ads especially in a foreign language has ruined the usability . I try to use my native health app now to avoid an ad at every click

**Developer response:** Hello, this is Once. :)

Thank you so much for using and loving Once, and we sincerely apologize for the inconvenience you experienced with the app.

We aimed to maintain an ad-free app for a long time, but we inevitably had to introduce ads to continue offering a free service to our users. We truly apologize once again for any frustration this has caused.

Warm regards,

Team Once

### 1/5 — Lost years of data

*2026-08-03, version 1.9.7*

Not logging in to facebook anymore all my data is there

### 4/5 — Good app.. but

*2026-08-01*

I’ve had this app for many years and it’s been great up until recently. 

The only thing I find annoying about this app is the ads when needing to add to the calendar. 

It would be nice to not have to watch a video every single time I need to mark the start of my cycle. 

Other than that this app has been great when tracking my cycle.

**Developer response:** Hello, this is ONCE :)
First of all, we’d like to thank you for your support of ONCE, and we apologize for any inconvenience this may cause while using the app.
We’ve long strived to provide an ad-free app, but in order to continue offering our service to users for free, we’ve had no choice but to include ads. We apologize once again for any inconvenience this may cause.

### 5/5 — 리뷰 한 번도 해본적 없는데

*2026-02-07*

달력에 주기대로 하는 건 원스뿐이고 몇년째 쓰는지 모르겠어요 감사합니다ㅜ 기가막히게 생리터지니까 밖에서 샐 일도 없고 다른 앱은 계산이 뭔가 이상한데 원스는 달마다 얼마치 했는지 간격은 어떤지 확인해줘서 최고의 앱입니다 삶의 질 상승ㅇㅇ 우리 오래봐요 원스..😌🩵

**Developer response:** 안녕하세요. 원스 입니다. :) 원스를 사랑해주셔서 정말 감사드립니다! 응원의 댓글과 별점은 저희에게 큰 힘이 된답니다! 감사합니다.

### 1/5 — Wont log in to facebook

*2026-01-03, version 1.9.5*

I recently got a new phone, im trying to log in with my facebook account and it won’t let me, I’ve been using this app for over 5 years now.

### 1/5 — Fix bug

*2025-07-14*

The app wont let me log in. Hence i cant use the in app features

### 2/5 — Synchronize

*2025-03-17*

I’ve used this app for years and for the past one it hasn’t synchronized once to my Google acct and is now stating that my personal information will be deleted. Such an unfortunate thing to happen on this app that I use monthly to track my cycle.  Please figure out the synchronize feature and lack of updating.  User since 2017.

### 5/5 — 好用，请问没有安卓版吗？

*2024-12-18*

请问没有安卓版吗？

### 5/5 — 非常好用的一款软件

*2024-09-29*

非常简洁好用的一款软件，陪伴我很多年了，我曾经还测试过其他的软件，都不行，太繁琐了（页面根本看不懂），就是ios18后彻底不支持小组件功能了（原来虽然不支持，但是还能看到），有点伤心💔，能请作者加上小组件的功能吗？就是倒计时一下就好，谢谢啦～

### 1/5 — Have to Watch an Ad Just to Record Data

*2024-05-15*

It's incredibly annoying. I'm just going to remove the download and find another app or manually record my dates now because it's ridiculous that I have to watch a 30 second ad just to record my period.

## Frequently asked questions about Once(A special period tracker)

### What does this period tracker app do?

This app functions as a comprehensive period tracker, helping women log their menstrual cycles, predict ovulation dates, and estimate fertile windows. It also calculates the possibility of pregnancy and allows users to record symptoms and intimate days.

### How accurate is the period prediction?

The app's period prediction becomes more accurate as you use it. It smartly calculates irregular period cycles and cramp. The fertile window and ovulation predictions are based on scientific calculations considering egg and sperm lifespans.

### Is this app free to use?

The app is free to download and use, offering core period tracking and prediction features. It also includes in-app purchases for additional functionalities or content, and may display advertisements.

### What are the key features of this app?

Key features include an estimated period calendar, ovulation and fertile window prediction, pregnancy percentage calculation, customizable reminders for important dates and contraception pills, a home screen widget for quick data access, and the ability to log symptoms and intimate days.

### Who is this app designed for?

This app is designed for women who need a reliable way to track their menstrual cycles, understand their fertility, and manage period-related symptoms. It caters to those who want a simple yet functional tool for their reproductive health.

## Version history (last 5 releases)

### 1.9.7 — 2026-07-29

fixed bugs.

### 1.9.6 — 2026-07-08

fixed bugs.

### 1.9.5 — 2025-08-13

We are fixing bugs and making improvements to provide a better Once experience.

### 1.9.4 — 2024-03-29

fixed bugs.

### 1.9.2 — 2024-03-15

fixed bugs.

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All apps by Malang Studio Co. Ltd,: https://appshunter.io/developer/523490027

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-09-09.*