Design an AI-powered feature recommendation system for a short-video app.
A direct proxy for TikTok's core recommendation engine — tests how you'd balance freshness, personalization, and latency at massive scale.
TikTokTikTok Software Engineer Interview Questions
TikTok's engineering challenges are defined by scale and speed: a recommendation system serving over a billion users, content and data pipelines processing enormous volume in real time, and product teams spread across time zones shipping features on a rapid cadence. Interviews are heavy on data structures, algorithms, and system design, with a strong emphasis on how a design behaves under real-world scale rather than in the abstract. Because teams collaborate globally, interviewers also probe for engineers who communicate clearly and can align with teammates they rarely meet in person.
What the interview process looks like
The loop usually starts with an online assessment (algorithmic problems under time pressure), followed by two to three technical interview rounds covering data structures/algorithms and system design, a cross-functional or hiring-manager round, and sometimes a bar-raiser interview focused on ownership and communication across distributed teams.
Example questions
Given a stream of video view events, design a system to compute trending content in near real time.
Checks understanding of streaming architectures and windowed aggregation, both central to how trending/For You feeds actually get built.
Write an algorithm to find the k most frequent items in a large, continuously updating dataset.
A practical algorithms question that mirrors the trending-content problem at a smaller, codeable scale.
How would you design a content moderation pipeline that needs to review video uploads within seconds?
Tests system design under strict latency constraints combined with the reality that automated and human review both need to fit in the pipeline.
Tell me about a time you had to coordinate a launch with a team in a very different time zone.
TikTok's engineering org spans multiple regions; this behavioral question filters for people who can hand off work asynchronously without losing context.
How would you design a system to A/B test a new ranking algorithm without degrading the experience for the control group?
Reflects how heavily TikTok relies on experimentation infrastructure to iterate on its feed — checks statistical and systems thinking together.
Given a list of user interactions, design a data model that supports both real-time personalization and long-term analytics.
Probes whether you can design for two very different access patterns (low-latency reads vs. batch analysis) off one underlying event stream.
Describe a situation where a product decision conflicted with a technical constraint you knew about. How did you resolve it?
Checks communication skills under pressure to ship fast, a constant tension on TikTok's product-velocity-driven teams.