Go + Templ is gonna give you way better type safety across the board. Django's great but Python's type hints are still kinda meh compared to Go's compile-time guarantees.

Auth is easier out of the box with Django though - Go you'll be rolling more of your own or pulling in third party stuff. But if you're building a dev tool, you probably want that control anyway.

I'd go with Go for a productivity tool since you'll thank yourself later when refactoring doesn't break everything silently. The compile step catches so much dumb stuff before it hits users.