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. 
nice initiative, will surely use it
Light-Light Decomposition?
Low Level Design
newbie AI blog typing "HLD" is like monkeys on a typewriter writing shakesphere
sorry but there's no AI in the blog or the platform as well.
wow i used this platform and ig its very much helpful if you need a start in system design.hopefully you guys would also like and use it