Need suggestions on my project idea

I'll go back to my boring project ideas. Take a closed source product and build its open source version.

I'm thinking of building an open source version of todoist. I'm in no rush, so I'll take my time.

I'll first build a web app for this and make it completely free. In the meantime, I'll build a desktop and mobile app and then make it local first and I'll start charging for sync.

Just like obsidian model

• I love todoist but they put stupid things behind the paywall that can be free.