Writing

Notes on systems, LLMs, and the industry building them.

I'm Wenhao, a software engineer. I write up system design problems I've worked through, what I'm learning about LLMs, notes from shipping side projects like ResumeMatch, and the occasional take on layoffs and where the industry is heading.

22 postsSince 2025
Tagged7 posts
Jul 21
Design a Coding Contest Platform like LeetCode

Design a coding contest platform that allows users to view problems, submit code, and compete in real-time programming contests. The system should su...

4 min read
Jul 18
Design a video streaming platform like YouTube

Designing a video streaming platform like YouTube is a classic and ambitious system design challenge. It involves building a highly scalable system c...

3 min read
Jul 13
Spotify Top K Songs

Designing a system to identify the top k heavy hitters in a data stream is a common yet challenging system design interview problem. Real-world examp...

3 min read
Jul 12
Key Concepts in System Design

Understanding core system design concepts is crucial for building scalable, performant, and reliable software systems. This post summarizes foundatio...

4 min read
Jul 10
Design a URL shortener like Bitly

Designing a URL shortener like Bitly is a classic beginner system design interview question. It involves creating a service that turns lengthy URLs i...

2 min read