Alex X

Alex X is a software engineer and author known for work in the machine-learning and systems-interview space. Machine Learning System Design Interview, co-written with Alex Xu, is a bestselling study guide that covers the core architecture patterns — feature pipelines, model training, serving, monitoring — tested in ML engineering interviews.

The author works as an engineering lead at a major technology company and interviews dozens of candidates a year. The book's popularity reflects a structural shift in the industry: engineering interviews that now lean on ML system architecture, and the enormous demand for clear, up-to-date preparation material.