Private by design · iPhone & Android

Your cycle,
kept close.

A calm, beautiful period tracker that lives only on your phone. No account. No ads. No eyes but yours.

Coming soon toApp Store

Coming soon toGoogle Play

Free to download
No sign-up
No ads, ever

No account needed
Zero ads
Nothing sent to a server
PIN & Face ID lock
Disguised icon on Android
Erase everything in one tap
No tracking SDKs
Beautifully calm design
No account needed
Zero ads
Nothing sent to a server
PIN & Face ID lock
Disguised icon on Android
Erase everything in one tap
No tracking SDKs
Beautifully calm design

Why Fern

Your period is personal.
Your app should be too.

Most cycle apps want an account, a cloud copy of your history, and a reason to show you ads. Fern does the opposite: everything you log lives on your phone — and nowhere else.

Features

Everything you need. Nothing you don’t.

Privacy

Stays on your phone. Full stop.

No account to create, no server to sync to, no copy anywhere else. Your cycle is a private file on the device in your hand.

Know what’s coming

Cycle day, phase, and roughly when your next period will arrive.

Locked to you

4-digit PIN plus Face ID or fingerprint. Fern re-locks the moment you leave.

Hide in plain sight Android

Make the home-screen icon and name look like Calculator, Notes, or Weather.

Patterns that are actually yours

After a few cycles, see how energy and mood shift — never guessed, always from your own notes.

Erase it all, instantly

Quick Clear wipes your log, PIN and settings from the phone in one tap.

Take a look

Calm by design. Made to feel like paper.

Know where you are, at a glance.

Open Fern and see your cycle day, your phase, and roughly how many days until your next period. That’s it — no feed, no noise.

Screens are faithful recreations of the app, shown with sample data.

Get started

Up and running in under a minute.

01
Tell Fern roughly when
Pick “about a week ago”, a date, or skip it. No account, no email — you’re in.
02
Check in when you feel like it
Flow, symptoms and a quick note. Log today, or any day you remember.
03
Glance at what’s next
Fern averages your recent cycles on your phone and shows when your next period is likely.

Where your data lives

Here. Only here.

There’s no Fern cloud, so there’s nothing to breach, sell, or hand over. Your history never leaves the phone it was written on.

No account, so there’s no login to leak.
Your log is stored in a database on your phone only.
Your PIN lives in the phone’s secure keychain.
No analytics, ad or crash-reporting SDKs in the app.
Never asks for location, contacts, camera or Health.

Made for you

Fern is for you if…

You just want to know when it’s coming

Without a sign-up form, a quiz, or a newsletter you never asked for.

Your phone gets borrowed

By a sibling, a partner, a curious friend. A PIN and a lock-on-leave keep your log yours.

You’ve read the headlines about period data

Fern has no server to hold your history. There’s simply nothing to hand over.

You’d rather not be the product

No ads and no tracking SDKs. Fern is built to be supported by the people who use it.

FAQ

Good questions. Honest answers.

Does what I log ever leave my phone?

No. Fern has no account and no server. Your entries live in a database on your device. Encrypted backup and importing from other apps aren’t built yet — and when they are, they’ll be opt-in.

Is Fern free?

Fern is free to download and downloading doesn’t start a subscription. It’s designed to be supported by its users, not by ads — a membership option is planned, but checkout isn’t connected in this version.

Can I use the fertile window to avoid or plan a pregnancy?

Please don’t. Fern estimates ovulation by counting back 14 days from your average cycle. It’s a calendar estimate of the dates you logged — not a test, not medical advice, and not a method of contraception.

Can I keep it private from people who use my phone?

Yes. Set a 4-digit PIN and unlock with Face ID or fingerprint. Fern locks again whenever you leave it. On Android you can make the icon look like Calculator, Notes or Weather, and Quick Clear erases everything in one tap.

What permissions does it ask for?

Only biometrics, so Face ID or your fingerprint can unlock Fern. It never asks for location, contacts, camera or Health access.

Which phones does it work on?

iPhone with iOS 13 or later, and Android phones. Android also gets a home-screen widget; the iPhone widget is on the way.

Take your cycle back.

Free to download. No account, no ads, no subscription to start. Just you and a quieter way to know your body.