I built the same app with GitHub Spec Kit and then OpenSpec: Tutorial & Comparison
Been using spec-driven development for a few months and kept seeing Spec Kit vs. OpenSpec comparisons that felt like they were written by people who hadn't actually used both. So I just built the same app twice.
Same stack (Next.js, Drizzle, PostgreSQL), same feature set, different SDD framework each time. Tracked token costs, session times, where I got stuck, where the AI went sideways.
A few things surprised me, particularly around token economics and how differently each tool handles context.
Curious if others have done similar experiments or landed somewhere different. I've compiled 2 tutorials + my findings and opiniated conclusions in a blog post and a few associated repos - will post them in a comment below.
What's your take on Spec Kit vs. OpenSpec?