Rabbit

October 2023 to February 2026. A startup that my friend and coworker Max and I co-founded. The source code is private, so it is not available to view.

Where this started

We both wanted to build good software for everyday people. We agreed on the shape of it: a consumer SaaS made of many small apps, each focused on one domain, all unified under the Rabbit name, the way Google and JetBrains each ship a family of tools. Each app would do one thing well, and one account would work across all of them.

The plan

We registered a company, opened a bank account and started coding. Candidate apps included budgeting, habits, nutrition tracking, resume software, notes, Bible verse memorization and a family calendar, all behind one login. People would pick the ones they needed.

What we built

We started with the platform, since every app would need it:

• An identity platform on OAuth 2.0 and OpenID Connect. Users sign in with a password, Google or Apple, and get access and refresh tokens. Other apps can offer "Sign in with Rabbit."
• The security details done properly: PKCE, CSRF protection, nonce checks, ID tokens, scope management, a consent screen for third parties, and role-based access control, so every future app could rely on it.
• A design system on Material UI: a color system with the usual semantic roles, typography, shadows and 25 drop-in components, packaged as a private npm package. The kit is live at kit.rabbit.dev and the site at rabbit.dev.

What it gave us

It was a fun and formative stretch. We built real systems end to end, from the security protocols to the design system to the sites, and learned OAuth 2.0 and OpenID Connect in depth, how security standards fit together, and how to build a design system people can pick up and use. It was a great way to grow as engineers, working side by side on something we cared about.

I left the project in February 2026, and the company continues under Max. I am glad we built it, and what I learned there carries straight into my work today, including Zeddius.