We last looked at JetBrains academy ~6 months ago and at the time it mostly had beginner-level content. Looks like they've got some advanced content now, like this one: https://hyperskill.org/projects/112?track=2.

I'd consider them a competitor, and I like their approach - hands-on project-based learning with automated tests to guide your implementation.

I think the primary difference (aside from their content being slightly skewed towards beginners and the limited languages on offer) is that our format involves re-creating devtools from scratch.