I make https://bedrock.mxstbr.com, selling a full-stack Next.js & GraphQL boilerplate for building SaaS products, which comes with:

* A complete TypeScript toolchain with end-to-end typesafety from the database to the client

* User authentication

* Subscription payments

* Teams

* Invitations

It's also completely unstyled, which is somewhat unusual in this space. I've found that most of the time, people would just delete all the styling anyway, so instead, the frontend only contains the minimal code necessary to make the functionality work.

I originally launched it in February last year, and it's still going strong now!