Moni | Devpost

Your Storybook Period Tracker
See your Whole Cycle at a Glance
Your Partner Gets Hints. Not Your Data.
Spot Patterns in Plan Words
Log Your Day By Just Talking
Here for Your Next Chapter
Know What Helps, Phase by Phase
Make Every Day Your Own Page
Calendar View(Month view)
Moni's Chat View
Today's Update Popup
Homepage
Insights

Inspiration

Moni started with my partner.

More than once, I only understood that a week had been hard after it was over, and I wished I'd known sooner how to help.

I wanted to show up better on those days, but none of the options were good. Asking every morning felt like an interrogation. A shared period calendar would show me far more than I needed to know and still not tell me what would actually help. And the trackers themselves were charts of red dots that nobody looks forward to opening.

So I built Moni around two ideas: the person tracking gets something that feels like a journal instead of a medical chart, and the people close to them get just enough to be kind, and nothing more.

What it does

Moni is a period tracker that reads like a storybook.

Every day is a painted page. Open any day to see its cycle phase with watercolor art, what's happening in your body, and what to eat, do, and skip.
Decorate the day. Draw on it, write notes by hand, or add from 170 3D stickers, including a shelf made for cycle days.
Ask Moni. An AI companion who knows what day of your cycle it is and what's coming next, and answers like a friend rather than a textbook.
Insights in plain words. Cycle length, irregularity, and PCOS-related patterns, explained simply, always marked as not medical advice.
Care Circle, the reason Moni exists. Invite a partner, parent, sibling, or friend with a one-time code. They get their own view: a soft "inner weather" for the day, concrete ways to help, and a push notification when something changes. You choose between Gentle (care hints only) and Phase vibe (adds a sense of the week's energy). They never see dates, cycle days, or intimate symptoms, and removing someone ends their access immediately.
Pregnancy mode. When the story changes, Moni switches to week-by-week tracking.

How I built it

One codebase, three platforms: Next.js 16 and React 19, exported as a static site and wrapped with Capacitor 8 for iPhone and Android, plus a web app.
Backend: Node.js and Express with Prisma on Neon Postgres.
AI: Claude through OpenRouter powers Moni's chat, with a fallback model.
Notifications: APNs, FCM, and Web Push, driven by a server-side scheduler.
Payments: RevenueCat for Moni Pro across iOS, Android, and web, plus AdMob rewarded ads verified on the server.
Sign-in: Apple and Google.
Design: a flat, ruled-paper planner look with one typeface (Inter) and original watercolor illustrations.

Partner privacy is enforced in code, not just promised in copy. Everything that reaches a supporter has to pass through a single PartnerSafeLog type that only holds mood and non-intimate symptoms. A raw day log can't compile into a partner's feed or lock-screen notification.

Challenges I ran into

Writing hints that help without revealing anything. "Keep plans light tonight" is useful; "day 2 of her period" is not okay. Every hint is written per phase and per relationship, because what reads as sweet from a spouse sounds strange from a parent.
Making revocation real. Removing someone from the circle has to revoke their link and expire any open invite codes in the same step, otherwise "remove" is just a UI change.
Making a web app feel native. Safe areas, push on three platforms, and purchases that stay in sync between iOS, Android, and the browser.
Honest feedback. An early tester said the drawing tools felt "like a note-taking app." I rebuilt the sticker set around the cycle instead of generic doodles.

Accomplishments that I'm proud of

Moni isn't a demo. It's a working product: an iPhone app, a web app, a landing page, and a privacy policy written from the actual server code.
The partner privacy boundary is checked by the compiler, not left to good intentions.

What I learned

The hardest decisions on the partner feature were about what to leave out. In a health app, what you choose not to share is what earns trust, and tone matters as much as features.