Simpluna
I've been running Simpluna, a period-tracking app, for six years. It's a company based in Tokyo, Japan, but development and operations are basically a one-person effort. The app is built with React Native (Expo). The defining trait of the app is that it's simple, with no unnecessary features. Recording periods, calculating predictions, and sending notifications — that's the core of it. This space is dominated by big players (Flo, Clue, and in Japan, Luna Luna). Building something similar would have been hopeless, so I made the things those apps don't have my selling point. Optional features…
Simpluna launched on July 14, 2021 with 68 votes, #1,096 of 3,502 launches that month and more than 50% of that year's launches. The site was still online in September 2026, 5 years on.
What it does
Simpluna is a simple period tracker with no ads and no account. Enter your period dates and the next period is predicted on a clean calendar. Private by design: your period data is stored only on your device, and nothing is required to start — no sign-up, no email, no personal profile. Cloud backup is optional and stays under your control. You can also lock the app with a passcode or Face ID. The paid Plus version is a one-time purchase, not a subscription. Over 600,000 downloads.
An app for recording your period and checking the next predicted date. No ads and no account registration.
Record your period and check the next predicted date. No ads or account registration are required. Your records stay on your device unless you enable cloud backup. Every paid option is a one-time purchase, with no subscriptions. Record the start and end of your period from the calendar and check the next predicted date. Choose how many days before your predicted period you want to receive a notification. A one-time purchase. There are no monthly or annual payments. Every additional feature can be turned on or off individually, so you can use only what you need. Show cycle days and the next predicted date above the calendar. Automatically save period records to Apple Health or Health…from simpluna.app
In the maker’s words, at launch
I've been running Simpluna, a period-tracking app, for six years. It's a company based in Tokyo, Japan, but development and operations are basically a one-person effort. The app is built with React Native (Expo). The defining trait of the app is that it's simple, with no unnecessary features. Recording periods…
Does a similar job
all alternatives →- IMI made a privacy friendly and simple app to track my menstruation2024 · play.google.com · ▲732
Hey HN, after the app I actually used to track my period wanted me to log in and save my data in the cloud, I decided to write my own. Most apps in this area are based on a subscription model and display far too much information anyway. For me, a simple calendar is enough where I can add a few notes if necessary. So that is the result of my work - a simple design and the data is only saved on the smartphone.
LadyLog - A period tracker2024 · play.google.com · ▲89Easy to use period tracking app that respects your privacy
Period-Calculator.com2020 · period-calculator.com · ▲63Privacy-first period calendar with smart predictions 📅
Luna - Private Period TrackerNov 2025 · apps.apple.com · ▲11Your period data never leaves your phone. 100% private.
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