PrepGrind is a interactive playground to learn system design and data structures, algorithms (DSA) & AI. Build architecture diagrams on a drag-and-drop canvas, run live traffic simulations, study 33 real system design case studies (URL shortener, Instagram, chat, video streaming, payments), and master DSA patterns with step-by-step algorithm visualizations and interview guides.
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Maker
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Hey Product Hunt ๐
I'm the solo maker behind PrepGrind.
I built it out of frustration. When I was prepping for system design interviews, everything was passive - reading articles, staring at static diagrams, memorizing answers I couldn't actually defend. I could say "add a cache to reduce database load," but I had no feel for how much it helped or what would break first under load. You just can't get that from a blog post.
So I made PrepGrind - a place where you actually build the system instead of reading about it:
๐งฉ Drag real components onto a canvas - load balancers, caches, queues, databases, even LLMs and vector DBs
โ๏ธ Configure each one (cache hit-rate, capacity, rate limits, load-balancer strategy)
๐ Push live traffic through it and watch real-time throughput, latency and error rates on every node
๐ด Crank the load until something turns red - it flags exactly what fails under pressure (bottlenecks, single points of failure)
๐ข Add capacity and watch it recover in real time
You learn the trade-off by seeing it, not memorizing it.
It's more than system design too - there are 35+ real case studies (URL shortener, chat, video streaming, RAG, recommendation enginesโฆ), a DSA pattern tracker with a personalized prep plan, and an interactive AI module that visually unpacks how things like attention, embeddings and RAG actually work.
It runs right in your browser - free to start, no signup needed.
I'm building this solo and would genuinely love your feedback:
๐ Does the simulation help your intuition, or does the approximation bug you?
๐ What case study or feature should I add next?
Thanks so much for checking it out ๐