I Built a Habit Tracker That Can't Read Your Habits
I'm Mark, co-founder of Moss Piglet, a family-founded public benefit company. I just launched our second product, Metamorphic — a habit tracker where all data is end-to-end encrypted and I literally cannot see any of it.
The backstory
I'd been building Mosslet, a privacy-first social platform with Bluesky interop, and had developed a zero-knowledge encryption flow for direct messages (after Meta’s announcement to remove it from their platform) on top of Elixir and Phoenix LiveView.
Several years ago, Mosslet was originally branded as Metamorphic, but I felt it didn’t match (especially when Facebook rebranded) and I’d been holding on to the brand assets trying to figure out what my next product would be for people.
That’s when I became inspired by my partner's background in psychology, behavioral science, and her passion for habit forming. She got me thinking about habit tracking — and it hit me that your habits, goals, and reflections are some of the most personal data you generate: a map of what you're trying to change about yourself. This feels like a goldmine for surveillance capitalists and every other habit tracker stores that in plaintext.
So I applied the encryption architecture from Mosslet’s direct messages to an entire new app: Metamorphic.
What it does
Habit tracking, goal setting with milestones, self-reflections with mood tracking, a schedule/calendar, family groups with shared accountability, and progress insights — all end-to-end encrypted. The server only ever sees ciphertext.
Video walkthrough here: https://www.youtube.com/watch?v=fGA4Op1Fqew
Zero-knowledge end-to-end encryption isn't a premium feature. Every tier gets it. Paid tiers gate convenience, not privacy.
Pricing:
Free — 5 habits, 7-day history, reminders, check-ins
Personal ($5/mo) — Unlimited habits, full history, progress insights, reflections, goals, schedule/calendar, data export
Family ($9/mo) — Everything in Personal + unlimited groups, shared habits, shared goals, group dashboard, member spotlights, group insights, group calendar
The numbers (honest)
Where we're at: Launched two weeks ago (or however long). Too early for meaningful numbers. Solo dev, bootstrapped, no VC. Revenue comes directly from users along with our feature/design choices.
What I've learned
Privacy is strangely a hard sell. Most people don't think about whether their habit tracker encrypts their data or is harvesting it for the surveillance industry. The default assumption is "it's fine, who cares about my habits?” And it’s not their fault, the industry is designed to do everything invisibly to the user, so they aren’t aware of it. This makes it even more challenging to make people care without scaring them or sounding paranoid (there’s a big gap between people saying “I love that” and taking action).
Emotional clarity beats technical accuracy in marketing. "We use XSalsa20-Poly1305 with hybrid ML-KEM-768 + X25519 post-quantum key encapsulation" means nothing to 99% of people. "We can't read your data, even if we wanted to" does all the work. Finding that translation layer is difficult and feels like a process of constant iteration and refinement.
Being a PBC actually matters to me. It's not just a label, but again, it’s all about trust. When you tell people "we'll never sell your data," they've heard that from every company that eventually sold their data. When you tell them "we architected the system so it's technically impossible," that's different.
Marketing and distribution is the next big challenge.
Building the product is always the fun part, seeing the “magic” work. Getting it in front of people — privacy-conscious who also care about habit tracking — is where I'm spending most of my energy now.
What's next
Scaling marketing, building out and refining new/existing features, and eventually native mobile apps. Also continuing to develop Mosslet alongside it — both products share the same privacy-first ethos.
If you try it, I'd especially appreciate feedback on anything and everything.
