About Rhythm
Why this exists
Most baby tracking apps fall into two categories: free apps that sell your data and show you ads, or expensive subscriptions that lock core features behind paywalls (BabyBuddy, a self hostable app, is a notable exception). I built Rhythm as the answer.
I used BabyBuddy and found myself staring at charts trying to figure out "How long will he be down", "When should I put him to bed", and "Which day is this most similar to? How did we feel that day?". That's all time-chunked pattern matching, so I moved the same process into an app.
What I believe
Your data is yours.
Rhythm is local-first. Everything runs on your device by default, including analytics and predictions. I don't see your data unless you choose to sync it.
The app should work when you need it most.
That's usually 3 AM, half-asleep, holding a baby. Midnight Mode exists because a bright screen at that hour is hostile. One-swipe logging exists because fumbling through menus while nursing is not a viable workflow.
Transparency over black boxes.
When Rhythm suggests a wake window, it shows you which data points led to that suggestion. If you think it's wrong, you can adjust it. I'd rather you trust your own instincts with data to back them up than blindly follow an algorithm.
Honest pricing.
The full app is free on one device. For $5/month, you get sync, backup, and household sharing. That's it. No "Basic" tier that's missing half the features. No ads, no tracking.
How it's built
Rhythm is a progressive web app. It runs in your browser and can be installed to your home screen. No app store needed. It works on iPhones, Android phones, tablets, and laptops. It works offline and auto-updates.
The sync infrastructure uses CouchDB as the database. Data is replicated across servers in separate geographic regions. I've tested sync extensively - all servers would need to go down for sync to truly fail, and since everything is IaC through Terraform and Ansible, I can stand them back up in a few minutes. Backups are stored (encrypted) in B2, taken daily. Analytics and predictions run entirely on your device - nothing is sent to a server for processing.
Who builds it
One dad, working every night while watching the baby monitor until he needs me. Some nights I work for a few hours, some nights he needs help as soon as I sit down. This went on for several months, and now I'm excited to share Rhythm with other parents.
If something is broken, I want to hear about it. If a feature doesn't make sense, I want to know. Email support@rhythm.baby.
How long will this be supported?
I plan to have a few more kids, and to actively use Rhythm for years to come - then continue maintenance for as long as the community needs it. If I were to step away, I'd work with the community to find a solution.