Over the past few weeks, I worked on building my first reusable SaaS starter kit using Next.js, Prisma, JWT authentication, and Lemon Squeezy billing.

The goal was simple:

Stop rebuilding the same foundation every time I start a new SaaS idea.

But while building it, I made a lot of mistakes — and honestly, those mistakes taught me more than the successful parts.

Here are some of the biggest lessons I learned.