17App developmentEveryday toolsSpec
An app for parents of twins, from birth to one year
An iPhone and Android app for logging feeds, diapers and sleep for two or three babies on one screen, one handed at 3 a.m., with your partner seeing it on their phone straight away.
Full version one spec written, no code yet
The challenge
The research I ran on the niche said don't build it. The big baby trackers already handle twins with a separate profile per baby, and at least nine twin specific apps that launched in 2025 and 2026 stayed at 0 to 11 ratings. The recommendation was a twins mode inside a general baby app. On the other hand, none of the leaders shows the babies side by side, and there is no twins app in Hebrew.
What I did
- One screen for all the babies, a column per baby, and "both" actions in a single tap. Every action sits in the lower part of the screen, so you can log with one hand while the other holds a baby.
- Real tandem feeding: two timers running together, a side for each baby, and the baby's name and color large on screen while nursing.
- "Who's next" as a fact, not an instruction. The label marks the baby who has gone longest since the last feed, with no arrow and no warning color.
- Each baby against their own growth curve, side by side, with nothing saying who is ahead or behind. Corrected age for preemies by default. The app does not diagnose, does not say what is normal and does not suggest doses. The standard preterm growth chart needs a license for a paid app, so I decided to launch without it and apply for the license in parallel.
- Free for one parent, with every measure included. You pay only for each additional person connected to the home: a second parent, a grandparent or a nanny. Sharing goes through my own server so it works between iPhone and Android.
The decision that made the difference
Building a separate app, against the research. A parent of twins told me they were missing "everything": one screen for both, fast logging for both, growth comparison and sync with their partner. Testimony from a real user outweighs a score built from reviews. From the research I kept what supports the decision: there is no twins app in Hebrew, which makes Israel the test market. That call set everything else: the app is built from the ground up for several babies, not as a single baby app with an extra profile bolted on.
What AI did, and what stayed with me
- AI agents did the research and the spec: the niche and competitor review, the spec for all seven screens, and a list of risks against Apple's guidelines for health apps.
The big decision I made against the research. The research said not to build a separate app. A parent of twins told me what they were missing, and I went with that. The name and the price I left to the dedicated agents, based on research.
Outcome
- A written spec for version one: seven screens, birth to one year, up to three babies, in Hebrew and English.
- Alongside the spec: a list of risks to check against Apple's guidelines for health apps, and open questions for pricing.
- No design, code or name yet.