Gaia Baby Tracker. A shared baby tracker for iPhone. One baby log for everyone.

Overview

Gaia is a free baby log that every caregiver shares. Each parent, grandparent or nanny signs in with their own account, and a feed, nap or diaper logged on one phone shows up on the others within seconds. No subscription, no paywall, no ads.

Why I built it

Gaia is our daughter’s middle name, and the app was our family’s log before it was anyone else’s. Nara Baby, the tracker every new parent we knew used, ended its free tier. Instead of paying, I built our own. Three days later we had a working build on our phones, and we’ve used it every day since.

The job is simple: nobody should have to send a text at 4am to ask when the last feed was.

My role

I designed and built Gaia on my own: the product, the interface and its illustrations, the iPhone app, the Apple Watch app and widgets, the API, the website and the App Store releases. Claude Code was my pair, co-authoring 330 of the repository’s 474 commits. How I made the brand, with the prompt that draws every character and the skill that holds the rest, is in How I built Gaia.

What it does

• One shared timeline for every caregiver. Invite someone with a six-character code. They see everything from before they joined, and anyone can stop a timer someone else started.
• Every kind of entry. Feeds, diapers, sleep, pumping, solids, tummy time, medicine and milestones, each two taps from the home screen, and twins supported.
• Nap prediction from recent wake windows, shown as a range.
• Growth charts against the WHO Child Growth Standards, with corrected age for babies born early.
• Import from other baby trackers or any CSV, so a family keeps its history.
• Everywhere it’s needed. Apple Watch, Home and Lock Screen widgets, a Live Activity for a running timer, offline logging, and eight languages.
• A read-only MCP connector, so a caregiver can ask an AI assistant about their baby’s real data.

Decisions and trade-offs

• Every caregiver free. The app is free and so is every person you invite, and someone who joins today sees the whole history, so a grandparent or a nanny starts with the full picture.
• Polling, not sockets. Rather than hold a socket open on a phone that’s always being suspended, the client polls: every four seconds while you’re looking, every twenty when idle, never in the background. Writes are optimistic with IDs made on the device, so a retry can’t duplicate an entry.
• One table for every tracker. One events table backs all eight kinds of entry, so the timeline is one query and sync is one cursor.
• Nothing measured leaves the phone to become a percentile. Growth percentiles are computed on the device.
• Say less when the science says less. The sleep chart shows the AASM and AAP ranges, and deliberately shows none under four months, the age those guidelines start at.
• Native where the system demands it. The Watch app is SwiftUI with no JavaScript: the phone hands it the session and the active child, then it talks to the API itself. Siri and Shortcuts run through App Intents compiled into the app, because only the app’s own process can end its Live Activity.
• Apple Health, one way. Gaia writes the parent’s lactation data and reads nothing.
• A small type and colour system. Figtree and Inter, seven sizes, nothing heavier than medium. Yellow is decoration and green is action, with one accent spent once per screen. One corner radius, and cards that sit darker than the ground. The illustrations start as drawn sheets and are traced and re-inked into vectors by script, so the same drawings run in the app, on the Watch and in the widgets.

How it’s built

The app is Expo and React Native in TypeScript, with SwiftUI for the Watch app and widgets. The API is one Vercel function over Neon Postgres, with Better Auth for accounts.

Authorization has two layers. The API scopes every query to the caller’s family, and Postgres row-level security enforces the same rule underneath, so a handler with a missing WHERE clause still can’t read another family’s log. With no identity set, every table returns zero rows.

Where the AI stops

A caregiver can connect Gaia to an AI assistant, and I drew the line for that connector before I wrote it. Access is read only and approved on gaiababy.app, not inside the assistant. It can pull up recent activity and work out factual summaries, but it can’t change the log, diagnose a child or turn a pattern into medical advice. It runs under the same row-level security as the app, so it sees one family’s records and nothing else.

The app holds the same line. Nap prediction is a range, not a promise. The Food section’s recipes and feeding guides are labelled as drafts and general information, not medical advice, until a registered dietitian has reviewed them.

Timeline

• 21 September 2026. First commit.
• 25 September. The first TestFlight builds.
• 2 October. The MCP connector, secured with OAuth.
• Early October. Live on the App Store.
• 8 October. App Review turns down 1.0.6.
• 11 October. 1.0.7 brings Apple Health.
• 12 October. 1.0.8, the first Apple Watch release, with widgets close behind.
• 18 October. 1.0.19 on sale.

Where it is now

Gaia is live on the App Store for iPhone and Apple Watch, free, in eight languages, and a post about it went viral with more than 100,000 views. Android isn’t available yet. A Food section with recipes, meal planning and feeding guides is in beta. More at gaiababy.app.