Prototyping without a backend

I've been prototyping a todo app (think: Superhuman for tasks) with no backend at all, instead just writing local data to the local storage in the browser. I did this mainly to simplify the initial development process and create focus around the UI, interactions and user experience. I knew going in that the most important part of this product will be super efficient UI interactions (example: full keyboard navigation for every function in the product), so I wanted to create a lot of space to work out the ideas I have in my head.

This has been incredibly productive and liberating, even as someone who's been very full-stack for over a decade and can build APIs very quickly. Being able to quickly toss things into a simple local storage "database" and focus on the UI has created a lot of momentum and velocity, enabling me to rapidly experiment with ideas for how the UI should feel and function. It makes the process feel much closer to creating art vs building software.

Of course, this doesn't make sense in all cases. But I wanted to focus this product around the interactions and user experience to build a todo app that is as fast as possible for the user and stays out of your way. Once the UI and interactions feel right, I'll build out the backend and plug it into the frontend.

This is the first time I've take this approach and I'm really enjoying it. Has anyone else taken this approach? Any good tools I should know about?