PrepCity is an AI interviewer that never goes easy on you. It catches bad math, challenges vague answers, and grades you on Google's L3-L7 scale. For coding, it derives solutions from observation - not memorization. Trace by hand, spot the pattern, code emerges naturally. For system design, it analyzes your architecture with graph algorithms to find flaws, then grills you on each one. Web, Android, Windows. Voice mode included. 236 topics. 74 coding problems.
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Maker
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Hey PH! I'm Adrian, solo developer behind PrepCity.
I built this because interview prep felt broken. You either watch hours of lectures, memorize solutions you forget in
a week, or pay $100+ per mock interview.
PrepCity takes a different approach:
- The mock interviewer is adversarial by design. It catches your math errors ("100M/86400 is not 1000 QPS"),
challenges hand-waving ("that's a textbook answer - what does it look like in production?"), and never says "great
question."
- DSA coaching derives code from observation, not presentation. You trace by hand, spot the pattern, then the loops
emerge naturally - like proof by induction.
- System design uses actual graph analysis on your architecture diagrams - BFS reachability, shortest paths, cycle
detection - to find flaws a human interviewer might miss.
- At the end, you get a scorecard: Google L3-L7 level assessment, hire/no-hire decision, dimension-by-dimension
rubric, and specific recommendations.
236 system design topics. 74 coding problems across 19 patterns. Voice mode for practicing out loud.
Would love feedback on the mock interview grading - that's where most of the engineering went.
Links - add these:
- https://prepcity.io (main)
- https://prepcity.io/download (apps)
- https://prepcity.io/problems (coding problems)
- https://prepcity.io/library (system design library)
X account: @prepcity_io