I'm ionik_0. Built Systema, a free system design + coding interview practice tool or a platform. I cannot currently support the contests system because I'm just a student, and I don't have enough money to upgrade my cloud plans to support contest system.

The interesting part: grading isn't just pass/fail... each checker returns PASS/FAIL/UNKNOWN, The design actually gets checked against criteria, so an incomplete diagram isn't marked wrong, just unproven. Every checker is mutation-tested to confirm it actually catches real design mistakes.

The latest upgrade was

Grading Engine Upgrade New APIs and Schema(database) grading

More upgrades will be coming in the future , which will be every exciting.

Free, no ads. click here to checkout feedback welcome, especially if PASS/FAIL/UNKNOWN sounds like overkill.