I built HLDArena — a LeetCode-style online judge for High-Level Design (HLD) & System Design

Hey everyone,
Practicing DSA is interactive because online judges immediately tell you if you hit AC or TLE, whereas practicing High-Level Design (HLD) / System Design usually means passively reading blogs with no way to test your architecture.
So I built HLDArena: https://hldarena.vercel.app
What it does:

• Draw & explain: Wire your system architecture on a whiteboard canvas and write a short plain-English HLD spec.
• Deterministic 60s simulation judge (zero LLM randomness): Stress-tests your design against viral traffic spikes, hotkey skew, DB crashes, p99 latency SLOs, and monthly cloud cost budgets.
• Objective verdicts & ratings: Gives AC, TLE, SPOF, OVER_BUDGET, etc., a scrubbable 60s telemetry replay, and a competitive rating graph across Easy → Expert HLD problems. It's free to try at https://hldarena.vercel.app — would love your feedback if you test out a problem!